Make release directions more comprehensive

Author: oschwald

README.dev.md

@@ -1,6 +1,14 @@
 Steps for releasing:
 
-1. Update CHANGELOG.md with release and date.
-2. Run `./dev-bin/release.sh`. This will build the phar, generate the docs,
+1. Review open issues and PRs to see if any can easily be fixed, closed, or
+   merged.
+2. Bump copyright year in `README.md`, if necessary.
+3. Review `CHANGELOG.md` for completeness and correctness. Update its release
+   date.
+4. Install or update [hub](https://github.com/github/hub) as it used by the
+   release script.
+5. Run `./dev-bin/release.sh`. This will build the phar, generate the docs,
    tag the release, push it to origin, and update the GH releases with the
    release notes and Phar.
+6. Verify the release on [GitHub](https://github.com/maxmind/GeoIP2-php/releases)
+   and [Packagist](https://packagist.org/packages/geoip2/geoip2).