Add releasing docs (#3292)

add releasing docs

doc/devel/contrib/README.md

@@ -5,3 +5,4 @@
  * [Coding Style](coding_style.md)
  * [Branching Model](branching.md)
  * [Rust and C++](rust-and-c++.md)
+ * [Releasing Taskwarrior](releasing.md)

doc/devel/contrib/releasing.md

@@ -0,0 +1,21 @@
+# Releasing Taskwarrior
+
+To release Taskwarrior, follow this process:
+
+- Create a release PR
+    - Update version in CMakeLists.txt
+    - Update Changelog
+    - get this merged
+- On `develop` after that PR merges, create a release tarball:
+  - `git clone . release-tarball`
+  - `cd release-tarball/`
+  - `cmake -S. -Bbuild`
+  - `make -Cbuild package_source`
+  - copy build/task-*.tar.gz elsewhere and delete the `release-tarball` dir
+  - NOTE: older releases had a `test-*.tar.gz` but it's unclear how to generate this
+- Update `stable` to the released commit and push upstream
+- Tag the commit as vX.Y.Z and push the tag upstream
+- Find the tag under https://github.com/GothenburgBitFactory/taskwarrior/tags and create a release from it
+  - Give it a clever title if you can think of one; refer to previous releases
+  - Include the tarball from earlier
+- Add a new item in `content/news` on https://github.com/GothenburgBitFactory/tw.org