Update brew update formula instructions

Author: na-ka-na

BUILDING

@@ -0,0 +1,7 @@
+## Release
+
+* Change version in `build.gradle` file
+* Run `gradle smokeTest` to run all the tests
+* Run `gradle distZip`. Zip file will be in `build/distributions` folder
+* Upload release to github
+* Update brew formula https://docs.brew.sh/How-To-Open-a-Homebrew-Pull-Request#submit-a-new-version-of-an-existing-formula: `brew bump-formula-pr excel-compare --url <new_release.zip> --sha256 <sha256 of new_release.zip>`