Remove lsp-haskell--get-root from docstring

~'lsp-haskell--get-root~ was an alias for ~'lsp--suggest-project-root~,
and was removed in commit 9c0203b.

However, it remained in this doc-string example value for
~lsp-haskell-server-wrapper-function~. Using it led to a confusing
bug (at least for me) where ~'lsp--server-binary-present?~ would return
~nil~, leading to the "lsp-haskell is not configured" message.

Using ~'lsp--suggest-project-root~ instead works as before.

Author: Emily Bourke

lsp-haskell.el

@@ -248,7 +248,7 @@ For example, use the following the start the process in a nix-shell:
    (append (list \"nix-shell\" \"-I\" \".\" \"--command\" )
            (list (mapconcat 'identity argv \" \"))
            )
-   (list (concat (lsp-haskell--get-root) \"/shell.nix\"))
+   (list (concat (lsp--suggest-project-root) \"/shell.nix\"))
    )
   )"
   :group 'lsp-haskell