Fix typo (#61)

Author: mscherer

source/docs/e5.error_and_none_propagation.md

@@ -22,7 +22,7 @@ fn main() {
 }
 
 fn complex_function() -> Option<&'static str> {
-    let x = get_an_optional_value()?; // if None, returns immidiately; if Some("abc"), set x to "abc"
+    let x = get_an_optional_value()?; // if None, returns immediately; if Some("abc"), set x to "abc"
 
     // some other code, ex
     println!("{}", x); // "abc" ; if you change line 19 `false` to `true` 
@@ -54,7 +54,7 @@ fn main() {
 }
 
 fn complex_function() -> Result<u64, String> {
-    let x = function_with_error()?; // if Err, returns immidiately; if Ok(255), set x to 255
+    let x = function_with_error()?; // if Err, returns immediately; if Ok(255), set x to 255
 
     // some other code, ex
     println!("{}", x); // 255 ; if you change line 20 `true` to `false`
@@ -108,4 +108,4 @@ fn main() -> std::io::Result<()> {
 //    Error: Os { code: 2, kind: NotFound, message: "No such file or directory" }
 ```
 
-> 💯 If you want to know about the all kind of errors `std::fs::File::open()` can produce, check the [error list on `std::fs::OpenOptions`](https://doc.rust-lang.org/std/fs/struct.OpenOptions.html#errors).
+> 💯 If you want to know about the all kind of errors `std::fs::File::open()` can produce, check the [error list on `std::fs::OpenOptions`](https://doc.rust-lang.org/std/fs/struct.OpenOptions.html#errors).