Add Emacs 29 docs for Eglot (#188)

This is a builtin package and most likely what Emacs users are going to
use.

I also submitted this to Emacs mailing list (w/ static-ls as backup).
This would be included in Emacs 31, making configuration not necessary
(provided static-ls is in your PATH).

Author: matthewbauer

README.md

@@ -263,6 +263,16 @@ You can technically use any LSP compliant client - for a generic one we generall
   :language-id "haskell"))
 ```
 
+Alternatively, if you would like to use `eglot` (a builtin package
+since Emacs 29), you can configure eglot like this:
+
+1. Give `static-ls` higher precedence than the default
+   `haskell-language-server-wrapper`:
+
+```
+  (add-to-list 'eglot-server-programs `(haskell-mode . ,(eglot-alternatives '("static-ls" ("haskell-language-server-wrapper" "--lsp")))))
+```
+
 ### Helix
 Modify your `languages.toml` config file to add the following: