Typos: codespell --skip="*.po" -w (#478)

Author: cclauss

CONTRIBUTING.rst

@@ -52,7 +52,7 @@ and squashed into a minimal set of commits. Each commit should include
 the necessary code, test, and documentation changes for a single "piece"
 of functionality.
 
-To be mergable, patches must:
+To be mergeable, patches must:
 
 - be rebased onto the latest master,
 - be automatically mergeable,

docs/about/contributing.rst

@@ -52,7 +52,7 @@ and squashed into a minimal set of commits. Each commit should include
 the necessary code, test, and documentation changes for a single "piece"
 of functionality.
 
-To be mergable, patches must:
+To be mergeable, patches must:
 
 - be rebased onto the latest master,
 - be automatically mergeable,

docs/usage/json.rst

@@ -9,7 +9,7 @@ Although :doc:`WaffleJS<javascript>` returns the status of all
 :ref:`samples <types-sample>`, it does so by exposing a Javascript
 object, rather than returning the data in a directly consumable format.
 
-In cases where a directly consumable format is preferrable,
+In cases where a directly consumable format is preferable,
 Waffle also exposes this data as JSON via the ``waffle_status`` view.