doc: simplify Homebrew installation instructions (#2007)

Removed brew tap requirement as SourceGit is now available in the official Homebrew Cask repository. 🎉🎉🎉🎉🎉🎉🎉🎉🎉

Author: ybeapps

README.md

@@ -104,9 +104,8 @@ For **Windows** users:
 
 For **macOS** users:
 
-* Thanks [@ybeapps](https://github.com/ybeapps) for making `SourceGit` available on `Homebrew`. You can simply install it with following command:
+* Thanks [@ybeapps](https://github.com/ybeapps) for making `SourceGit` available on `Homebrew`:
   ```shell
-  brew tap ybeapps/homebrew-sourcegit
   brew install --cask sourcegit
   ```
 * If you want to install `SourceGit.app` from GitHub Release manually, you need run following command to make sure it works: