chore(docs): make changelogs visible on docsrs

Split changelog file to make it more comprehensible when reading and
also make it a part of documentation so it'll be more discoverable
by the users. This change also makes it possible for rust code inside
the changelogs to be tested with `cargo`.

Co-authored-by: Kirill Chibisov <contact@kchibisov.com>

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,5 +1,5 @@
 - [ ] Tested on all platforms changed
-- [ ] Added an entry to `CHANGELOG.md` if knowledge of this change could be valuable to users
+- [ ] Added an entry to the `changelog` module if knowledge of this change could be valuable to users
 - [ ] Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
 - [ ] Created or updated an example program if it would help users understand this functionality
 - [ ] Updated [feature matrix](https://github.com/rust-windowing/winit/blob/master/FEATURES.md), if new features were added or implemented

.github/workflows/ci.yml

@@ -190,7 +190,7 @@ jobs:
       if: matrix.toolchain == 'nightly'
       run: cargo doc --no-deps $OPTIONS --features=rwh_04,rwh_05,rwh_06,serde,mint,android-native-activity
       env:
-        RUSTDOCFLAGS: '--deny=warnings ${{ matrix.platform.rustflags }} --cfg=docsrs'
+        RUSTDOCFLAGS: '--deny=warnings ${{ matrix.platform.rustflags }} --cfg=docsrs --cfg=unreleased_changelogs'
 
     # See restore step above
     - name: Save cache of cargo folder

.github/workflows/docs.yml

@@ -17,7 +17,7 @@ jobs:
       contents: read
       pages: write
       id-token: write
-    
+
     steps:
       - uses: actions/checkout@v3
 
@@ -27,7 +27,7 @@ jobs:
 
       - name: Run Rustdoc
         env:
-          RUSTDOCFLAGS: --crate-version master --cfg=docsrs
+          RUSTDOCFLAGS: --crate-version master --cfg=docsrs --cfg=unreleased_changelogs
         run: |
           cargo doc --no-deps -Z rustdoc-map -Z rustdoc-scrape-examples --features=rwh_04,rwh_05,rwh_06,serde,mint,android-native-activity