Update changelog for v1.5

Signed-off-by: Peter Grayson <pete@jpgrayson.net>

CHANGELOG.md

@@ -1,5 +1,31 @@
 # Changelog
 
+## [1.5] 2022-01-28
+
+### Removed
+### Added
+- Add Makefile targets for installing shell completions
+- `stg rebase --interactive` learns 'hide' instruction
+
+### Changed
+- Picked patch names are preserved when possible (#175)
+- Replace `--unapplied` option with `--noapply` for `stg pick` (#174)
+- `stg pick --noapply` no longer reverses patch order (#174)
+- Use `stg version` uses `sys.executable` to get Python version.
+
+### Fixed
+- Repair `stg repair` with amended first patch (#163)
+- Repair corner cases where invalid patchnames could be generated by
+  `stg new`, `stg uncommit`, etc. (#176)
+- `stg mail` could crash due to a misspelled reference (#178)
+- Zsh completion for `stg refresh -p` now completes against all patches
+  (not just applied patches).
+- Zsh gains missing completion for `stg push --noapply`
+- Minor repair to help for `stg float --noapply` and `stg push
+  --noapply`
+- Restore `stg sink --nopush` capability.
+
+
 ## [1.4] 2021-10-27
 
 ### Removed