Update README.md to delete old bin

Previous versions of LunarVim had the bin located in `/usr/local/bin/lvim`.

Since the new one is at `.local/bin/lvim`, if $PATH has the previous bin location before the new one, new installations on systems that had already LunarVim installed in the past, will fail to work.

Hence, the old one should be removed.

README.md

@@ -28,6 +28,8 @@ You can find all of the documentation for Lunarvim at [lunarvim.org](https://www
 
 Make sure you have the release version of Neovim (0.5).
 
+If you have previously installed LunarVim, make sure to remove `/usr/local/bin/lvim`, as we've moved to `.local/bin/lvim`
+
 ``` bash
 bash <(curl -s https://raw.githubusercontent.com/lunarvim/lunarvim/master/utils/installer/install.sh)
 ```