chore: update docs about changelog usage

CONTRIBUTING.md

@@ -48,17 +48,16 @@ For an example of this process, see PRs
 
 ### Documentation Updates
 
-- Any major changes should be added to the [CHANGELOG](CHANGELOG.md)[*].
+- Any changes should be added to the Changelog via
+  [Changelog Fragments](changelog.d/README.md) (note that there is a separate
+  changelog for the [signer](stacks-signer/changelog.d/README.md)).
 - Mention any required documentation changes in the description of your pull request.
 - If adding or updating an RPC endpoint, ensure the change is documented in the
   OpenAPI spec: [`./docs/rpc/openapi.yaml`](./docs/rpc/openapi.yaml).
 - If your code adds or modifies any major features (struct, trait,
   test, module, function, etc.), each should be documented according
   to our [coding guidelines](#Coding-Guidelines).
 
-> [*] The Changelog focuses on product changes. A "major change" refers to updates that have a direct impact on the end user, such as introducing new features, modifying existing functionality, or optimizing runtime performance.
-On the other hand, changes that do not need to be reflected in the Changelog include code refactoring, writing tests, or automating processes, as these do not directly affect the user experience.
-
 ## Git Commit Messages
 
 Aim to use descriptive git commit messages. We try to follow [conventional commits](https://www.conventionalcommits.org/en/v1.0.0/).

changelog.d/README.md

@@ -1,8 +1,15 @@
 # Changelog Fragments
 
+The changelog helps developers keep track of the changes happening across the
+codebase. All PRs, other than those which are purely "chore" tasks (e.g.
+formatting, typos) should include a changelog entry. The changelog is NOT
+limited to only user-facing changes.
+
 Instead of editing `CHANGELOG.md` directly, each PR should add a **fragment
 file** to this directory. This avoids merge conflicts and makes the release
-process clearer.
+process clearer. Each fragment should be one or more complete sentences. Each
+line in the fragment file will become a separate bullet point in the final
+CHANGELOG.md.
 
 ## How to add a changelog entry
 

stacks-signer/changelog.d/README.md

@@ -1,8 +1,15 @@
 # Changelog Fragments (Signer)
 
+The changelog helps developers keep track of the changes happening across the
+codebase. All PRs, other than those which are purely "chore" tasks (e.g.
+formatting, typos) should include a changelog entry. The changelog is NOT
+limited to only user-facing changes.
+
 Instead of editing `CHANGELOG.md` directly, each PR should add a **fragment
 file** to this directory. This avoids merge conflicts and makes the release
-process clearer.
+process clearer. Each fragment should be one or more complete sentences. Each
+line in the fragment file will become a separate bullet point in the final
+CHANGELOG.md.
 
 ## How to add a changelog entry