Two spelling fixes from aspell

Author: alexwlchan

source/contributing.rst

@@ -121,8 +121,8 @@ version of your contribution for feedback in no way prejudices your chances of
 getting that contribution accepted, and can save you from putting a lot of work
 into a contribution that is not suitable for the project.
 
-Contribution Suitablility
-~~~~~~~~~~~~~~~~~~~~~~~~~
+Contribution Suitability
+~~~~~~~~~~~~~~~~~~~~~~~~
 
 The maintainers of a sub-project have the last word on whether or
 not a contribution is suitable for that project. We consider all contributions,

source/one-of-the-team.rst

@@ -26,7 +26,7 @@ Responsibility
 
 Becoming a contributor grants you quite a lot of power: in particular, you can
 merge pull requests and close bug reports. These can potentially give
-mischevious or malicious individuals the ability to cause a great deal of
+mischievous or malicious individuals the ability to cause a great deal of
 annoyance for everyone else.
 
 That's not a reason not to share these powers: we believe our community is full