release process: clarify change log updates

Author: jonasnick

doc/release-process.md

@@ -37,7 +37,9 @@ gcc -o ecdsa examples/ecdsa.c -I $dir/include -L $dir/lib*/ -l secp256k1 && ./ec
 ## Regular release
 
 1. Open a PR to the master branch with a commit (using message `"release: prepare for $MAJOR.$MINOR.$PATCH"`, for example) that
-   * finalizes the release notes in [CHANGELOG.md](../CHANGELOG.md) (make sure to include an entry for `### ABI Compatibility`),
+   * finalizes the release notes in [CHANGELOG.md](../CHANGELOG.md) by
+       * adding a section for the release (make sure that the version number is a link to a diff between the previous and new version) and
+       * including an entry for `### ABI Compatibility` if it doesn't exist,
    * sets `_PKG_VERSION_IS_RELEASE` to `true` in `configure.ac`, and
    * if this is not a patch release
        * updates `_PKG_VERSION_*` and `_LIB_VERSION_*`  in `configure.ac` and