Add troubleshooting note for Fedora

Fixes elixir-lsp#231

README.md

@@ -217,6 +217,8 @@ If you get an error like the following immediately on startup:
 
 and you installed Elixir and Erlang from the Erlang Solutions repository, you may not have a full installation of erlang. This can be solved with `sudo apt-get install esl-erlang`. Originally reported in [#208](https://github.com/elixir-lsp/elixir-ls/issues/208).
 
+On fedora if you only install the elixir package you will not have a full erlang installation, this can be fixed by running `sudo dnf install erlang` (reported in [#231](https://github.com/elixir-lsp/elixir-ls/issues/231))
+
 ## Known Issues/Limitations
 
 * `.exs` files don't return compilation errors