Remove custom Homebrew tap from instructions

Now that lazygit has been added to the Homebrew core repository
([1] [2]), Homebrew users no longer need to tap into
`jesseduffield/lazygit` to install it.

[1]: https://github.com/jesseduffield/lazygit/issues/256

[2]: https://github.com/Homebrew/homebrew-core/pull/37614

README.md

@@ -21,7 +21,6 @@ Jira? This is the app for you!
 ### Homebrew
 
 ```sh
-brew tap jesseduffield/lazygit
 brew install lazygit
 ```