Small corrections to GraphQL style guide

doc/development/api_graphql_styleguide.md

@@ -79,7 +79,7 @@ Requests time out at 30 seconds.
 ## Breaking changes
 
 The GitLab GraphQL API is [versionless](https://graphql.org/learn/best-practices/#versioning) which means
-developers must familiarize themselves with our [deprecation cycle of breaking changes](#breaking-changes).
+developers must familiarize themselves with our [Deprecation and Removal process](../api/graphql/index.md#deprecation-and-removal-process).
 
 Breaking changes are:
 
@@ -890,7 +890,7 @@ The main use case for this is one resolver to find all items, and another to
 find one specific one. For this, we supply convenience methods:
 
 - `BaseResolver.single`, which constructs a new resolver that selects the first item.
-- `BaseResolver.last`, with constructs a resolver that selects the last item.
+- `BaseResolver.last`, which constructs a resolver that selects the last item.
 
 The correct singular type is inferred from the collection type, so we don't have
 to define the `type` here.
@@ -996,7 +996,7 @@ end
 For this reason, whenever you call a resolver (mainly in tests - as framework
 abstractions Resolvers should not be considered re-usable, finders are to be
 preferred), remember to call the `ready?` method and check the boolean flag
-before calling `resolve`! An example can be seen in our [`GraphQLHelpers`](https://gitlab.com/gitlab-org/gitlab/-/blob/2d395f32d2efbb713f7bc861f96147a2a67e92f2/spec/support/helpers/graphql_helpers.rb#L20-27).
+before calling `resolve`! An example can be seen in our [`GraphqlHelpers`](https://gitlab.com/gitlab-org/gitlab/-/blob/2d395f32d2efbb713f7bc861f96147a2a67e92f2/spec/support/helpers/graphql_helpers.rb#L20-27).
 
 ### Look-Ahead
 
@@ -1184,7 +1184,7 @@ are returned as the result of the mutation.
 
 The service-oriented architecture in GitLab means that most mutations call a Create, Delete, or Update
 service, for example `UpdateMergeRequestService`.
-For Update mutations, a you might want to only update one aspect of an object, and thus only need a
+For Update mutations, you might want to only update one aspect of an object, and thus only need a
 _fine-grained_ mutation, for example `MergeRequest::SetWip`.
 
 It's acceptable to have both fine-grained mutations and coarse-grained mutations, but be aware