use contributions more consistently per annevk feedback

Used "trivial contribution(s)" consistently to refer to the concept, and only refer to change or changes when it is the literal meaning in context in a sentence. Good suggestion @annevk

Workstream Policy.md

@@ -105,12 +105,12 @@ The [Steering Group] approves new [Workstreams][Workstream] and determines the [
 
 ##### Trivial contributions
 
-Trivial changes may be accepted without coverage from the agreement. A trivial change is one that fits one of the following categories:
+Trivial contributions may be accepted without coverage from the agreement. A trivial contribution is one that fits one of the following categories:
 
 * Makes no changes to the visible text content (for example, fixing broken links, style sheets or markup).
 * Does not affect conformance (e.g., corrects a typographic error in a descriptive sentence), which should not change architectural or interoperability requirements for an implementation. Such changes should be small in scope (e.g., on the order of a few dozen characters changed at most); correcting non-normative code examples where the code clearly conflicts with normative requirements is fine, adding new non-normative code examples is not.
 
-If there is any doubt or disagreement as to whether requirements are changed, such changes should not be considered trivial.
+If there is any doubt or disagreement as to whether requirements are changed, such contributions should not be considered trivial.
 
 #### Withdrawing contributions