L2SS-259: Improve spelling and grammar

devices/test/README.md

@@ -69,9 +69,9 @@ and adding _test__ to the beginning. Below is an example:
 
 ## Mocking
 
-Contrarily to many other programming languages, it is entirely possible to
+Contrary to many other programming languages, it is entirely possible to
 modify **any** function, object, file, import at runtime. This allows for a
-great of flexibility but also simplicity in the case of unit tests.
+great deal of flexibility but also simplicity in the case of unit tests.
 
 Isolating functions is as simple as mocking any of the classes or functions it
 uses and modifying its return values such as specific behavior can be tested.
@@ -95,7 +95,7 @@ def function_under_test(self):
 def test_function_under_test(self, m_special_char):
     """ Test functionality of `function_under_test`
 
-    This mock decorator _temporarily_ overwrittes the :py:func:`special_char`
+    This mock decorator _temporarily_ overwrites the :py:func:`special_char`
     function within :py:module:`our_custom_module`. We get access to this
     mocked object as function argument. Concurrent dependencies of these mock
     statements are automatically solved by stestr.