Add a bit more prose and some links to the README (#2090)

Author: michaelpj

README.md

@@ -19,4 +19,10 @@
 [badge-codetriage]: https://www.codetriage.com/haskell/haskell-language-server/badges/users.svg
 [codetriage]:https://www.codetriage.com/haskell/haskell-language-server
 
-Haskell language server implementation. Consult the [project documentation](https://haskell-language-server.readthedocs.io/en/latest/) for more details.
+The official Haskell language server (LSP) implementation. Consult the [project documentation](https://haskell-language-server.readthedocs.io/en/latest/) for more details.
+
+- [Features](https://haskell-language-server.readthedocs.io/en/latest/features.html)
+- [Installation](https://haskell-language-server.readthedocs.io/en/latest/installation.html)
+- [Configuration](https://haskell-language-server.readthedocs.io/en/latest/configuration.html)
+- [Troubleshooting](https://haskell-language-server.readthedocs.io/en/latest/troubleshooting.html)
+- [Contributing](https://haskell-language-server.readthedocs.io/en/latest/contributing/index.html)