markdown consistency (TheAlgorithms#4461)

* markdown consistency

* Swap ** for __

Co-authored-by: Christian Clauss <[email protected]>

Author: vivian-dai

CONTRIBUTING.md

@@ -2,7 +2,7 @@
 
 ## Before contributing
 
-Welcome to [TheAlgorithms/Python](https://github.com/TheAlgorithms/Python)! Before sending your pull requests, make sure that you **read the whole guidelines**. If you have any doubt on the contributing guide, please feel free to [state it clearly in an issue](https://github.com/TheAlgorithms/Python/issues/new) or ask the community in [Gitter](https://gitter.im/TheAlgorithms).
+Welcome to [TheAlgorithms/Python](https://github.com/TheAlgorithms/Python)! Before sending your pull requests, make sure that you __read the whole guidelines__. If you have any doubt on the contributing guide, please feel free to [state it clearly in an issue](https://github.com/TheAlgorithms/Python/issues/new) or ask the community in [Gitter](https://gitter.im/TheAlgorithms).
 
 ## Contributing
 
@@ -15,9 +15,9 @@ We are very happy that you consider implementing algorithms and data structure f
 - Your work will be distributed under [MIT License](LICENSE.md) once your pull request is merged
 - You submitted work fulfils or mostly fulfils our styles and standards
 
-**New implementation** is welcome! For example, new solutions for a problem, different representations for a graph data structure or algorithm designs with different complexity but **identical implementation** of an existing implementation is not allowed. Please check whether the solution is already implemented or not before submitting your pull request.
+__New implementation__ is welcome! For example, new solutions for a problem, different representations for a graph data structure or algorithm designs with different complexity but __identical implementation__ of an existing implementation is not allowed. Please check whether the solution is already implemented or not before submitting your pull request.
 
-**Improving comments** and **writing proper tests** are also highly welcome.
+__Improving comments__ and __writing proper tests__ are also highly welcome.
 
 ### Contribution
 
@@ -33,7 +33,7 @@ An Algorithm is one or more functions (or classes) that:
 * take one or more inputs,
 * perform some internal calculations or data manipulations,
 * return one or more outputs,
-* have minimal side effects (Ex. print(), plot(), read(), write()).
+* have minimal side effects (Ex. `print()`, `plot()`, `read()`, `write()`).
 
 Algorithms should be packaged in a way that would make it easy for readers to put them into larger programs.
 
@@ -42,7 +42,7 @@ Algorithms should:
 * use Python naming conventions and intuitive variable names to ease comprehension
 * be flexible to take different input values
 * have Python type hints for their input parameters and return values
-* raise Python exceptions (ValueError, etc.) on erroneous input values
+* raise Python exceptions (`ValueError`, etc.) on erroneous input values
 * have docstrings with clear explanations and/or URLs to source materials
 * contain doctests that test both valid and erroneous input values
 * return all calculation results instead of printing or plotting them
@@ -66,10 +66,10 @@ pre-commit run --all-files --show-diff-on-failure
 
 We want your work to be readable by others; therefore, we encourage you to note the following:
 
-- Please write in Python 3.7+. For instance:  __print()__ is a function in Python 3 so __print "Hello"__ will _not_ work but __print("Hello")__ will.
+- Please write in Python 3.7+. For instance:  `print()` is a function in Python 3 so `print "Hello"` will *not* work but `print("Hello")` will.
 - Please focus hard on naming of functions, classes, and variables.  Help your reader by using __descriptive names__ that can help you to remove redundant comments.
-  - Single letter variable names are _old school_ so please avoid them unless their life only spans a few lines.
-  - Expand acronyms because __gcd()__ is hard to understand but __greatest_common_divisor()__ is not.
+  - Single letter variable names are *old school* so please avoid them unless their life only spans a few lines.
+  - Expand acronyms because `gcd()` is hard to understand but `greatest_common_divisor()` is not.
   - Please follow the [Python Naming Conventions](https://pep8.org/#prescriptive-naming-conventions) so variable_names and function_names should be lower_case, CONSTANTS in UPPERCASE, ClassNames should be CamelCase, etc.
 
 - We encourage the use of Python [f-strings](https://realpython.com/python-f-strings/#f-strings-a-new-and-improved-way-to-format-strings-in-python) where they make the code easier to read.
@@ -81,7 +81,7 @@ We want your work to be readable by others; therefore, we encourage you to note
   black .
   ```
 
-- All submissions will need to pass the test __flake8 . --ignore=E203,W503 --max-line-length=88__ before they will be accepted so if possible, try this test locally on your Python file(s) before submitting your pull request.
+- All submissions will need to pass the test `flake8 . --ignore=E203,W503 --max-line-length=88` before they will be accepted so if possible, try this test locally on your Python file(s) before submitting your pull request.
 
   ```bash
   python3 -m pip install flake8  # only required the first time
@@ -134,15 +134,15 @@ We want your work to be readable by others; therefore, we encourage you to note
   python3 -m doctest -v my_submission.py
   ```
 
-  The use of the Python builtin __input()__ function is **not** encouraged:
+  The use of the Python builtin `input()` function is __not__ encouraged:
 
   ```python
   input('Enter your input:')
   # Or even worse...
   input = eval(input("Enter your input: "))
   ```
 
-  However, if your code uses __input()__ then we encourage you to gracefully deal with leading and trailing whitespace in user input by adding __.strip()__ as in:
+  However, if your code uses `input()` then we encourage you to gracefully deal with leading and trailing whitespace in user input by adding `.strip()` as in:
 
   ```python
   starting_value = int(input("Please enter a starting value: ").strip())
@@ -175,8 +175,8 @@ We want your work to be readable by others; therefore, we encourage you to note
 - All submissions will be tested with [__mypy__](http://www.mypy-lang.org) so we encourage to add [__Python type hints__](https://docs.python.org/3/library/typing.html) where it makes sense to do so.
 
 - Most importantly,
-  - **Be consistent in the use of these guidelines when submitting.**
-  - **Join** [Gitter](https://gitter.im/TheAlgorithms) **now!**
+  - __Be consistent in the use of these guidelines when submitting.__
+  - __Join__ [Gitter](https://gitter.im/TheAlgorithms) __now!__
   - Happy coding!
 
 Writer [@poyea](https://github.com/poyea), Jun 2019.