docs: link to changelogs in published crate READMEs (#485)

This just seemed kinda nice to add.

bitfield/README.md

@@ -3,6 +3,7 @@
 🍄 bitfield utilities, courtesy of [Mycelium].
 
 [![crates.io][crates-badge]][crates-url]
+[![Changelog][changelog-badge]][changelog-url]
 [![Documentation][docs-badge]][docs-url]
 [![Documentation (HEAD)][docs-main-badge]][docs-main-url]
 [![MIT licensed][mit-badge]][mit-url]
@@ -11,6 +12,9 @@
 
 [crates-badge]: https://img.shields.io/crates/v/mycelium-bitfield.svg
 [crates-url]: https://crates.io/crates/mycelium-bitfield
+[changelog-badge]:
+    https://img.shields.io/crates/v/mycelium-bitfield?label=changelog&color=blue
+[changelog-url]: https://github.com/hawkw/mycelium/blob/main/mycelium-bitfield/CHANGELOG.md
 [docs-badge]: https://docs.rs/mycelium-bitfield/badge.svg
 [docs-url]: https://docs.rs/mycelium-bitfield
 [docs-main-badge]: https://img.shields.io/netlify/3ec00bb5-251a-4f83-ac7f-3799d95db0e6?label=docs%20%28main%20branch%29

cordyceps/README.md

@@ -3,6 +3,7 @@
 🍄 the [Mycelium] intrusive data structures library.
 
 [![crates.io][crates-badge]][crates-url]
+[![Changelog][changelog-badge]][changelog-url]
 [![Documentation][docs-badge]][docs-url]
 [![Documentation (HEAD)][docs-main-badge]][docs-main-url]
 [![MIT licensed][mit-badge]][mit-url]
@@ -11,6 +12,9 @@
 
 [crates-badge]: https://img.shields.io/crates/v/cordyceps.svg
 [crates-url]: https://crates.io/crates/cordyceps
+[changelog-badge]:
+    https://img.shields.io/crates/v/cordyceps?label=changelog&color=blue
+[changelog-url]: https://github.com/hawkw/mycelium/blob/main/cordyceps/CHANGELOG.md
 [docs-badge]: https://docs.rs/cordyceps/badge.svg
 [docs-url]: https://docs.rs/cordyceps
 [docs-main-badge]: https://img.shields.io/netlify/3ec00bb5-251a-4f83-ac7f-3799d95db0e6?label=docs%20%28main%20branch%29
@@ -106,4 +110,4 @@ The following features are available (this list is incomplete; you can help by [
 [queue]: https://docs.rs/cordyceps/latest/cordyceps/mpsc_queue/struct.MpscQueue.html
 [`Linked`]: https://docs.rs/cordyceps/latest/cordyceps/trait.Linked.html
 [`liballoc`]: https://doc.rust-lang.org/alloc/
-[`libstd`]: https://doc.rust-lang.org/std/
+[`libstd`]: https://doc.rust-lang.org/std/

maitake-sync/README.md

@@ -4,14 +4,18 @@
 primitives from [`maitake`]
 
 [![crates.io][crates-badge]][crates-url]
+[![Changelog][changelog-badge]][changelog-url]
 [![Documentation][docs-badge]][docs-url]
 [![Documentation (HEAD)][docs-main-badge]][docs-main-url]
 [![MIT licensed][mit-badge]][mit-url]
 [![Test Status][tests-badge]][tests-url]
 [![Sponsor @hawkw on GitHub Sponsors][sponsor-badge]][sponsor-url]
 
 [crates-badge]: https://img.shields.io/crates/v/maitake-sync.svg
-[crates-url]: https://crates.io/crates/maitake-sync-sync
+[crates-url]: https://crates.io/crates/maitake-sync
+[changelog-badge]:
+    https://img.shields.io/crates/v/maitake-sync?label=changelog&color=blue
+[changelog-url]: https://github.com/hawkw/mycelium/blob/main/maitake-sync/CHANGELOG.md
 [docs-badge]: https://docs.rs/maitake-sync/badge.svg
 [docs-url]: https://docs.rs/maitake-sync
 [docs-main-badge]: https://img.shields.io/netlify/3ec00bb5-251a-4f83-ac7f-3799d95db0e6?label=docs%20%28main%20branch%29