Simplify Neovim installation instruction

Users don't have to interact with low-level `nvim.lsp` API anymore, they
can use the official `nvim-lspconfig`

I'd love to merge neovim.md directly into the README, but given these
lines:

> You can find a standalone LSP launch script in kotlin-lsp.sh along with
> very experimental (aka "works on someone's machine") instructions that
> setup LSP for other editors in scripts folder. See ./kotlin-lsp.sh
> --help for available options.

I don't dare to do so

Author: nikitabobko

scripts/neovim.md

@@ -1,44 +1,5 @@
-# neovim setup
+# Neovim setup
 
-## stdio way
-
-1. Ensure socat and netcat are installed
-
-2. Ensure `kotlin-lsp.sh` is executable
-   
-    ```sh
-    chmod +x $KOTLIN_LSP_DIR/kotlin-lsp.sh
-    ```
-
-3. Create a symlink inside your `PATH` to `kotlin-lsp.sh` script, e.g.:
-
-    ```sh
-    ln -s $KOTLIN_LSP_DIR/kotlin-lsp.sh $HOME/.local/bin/kotlin-lsp
-    ```
-
-4. Configure [nvim.lsp](https://neovim.io/doc/user/lsp.html) e.g:
-    ```lua
-    {
-      cmd = { "kotlin-lsp", "--stdio" },
-      single_file_support = true,
-      filetypes = { "kotlin" },
-      root_markers = { "build.gradle", "build.gradle.kts", "pom.xml" },
-    }
-    ```
-
-## tcp way
-
-Requires manual launch of language server
-
-1. launch language server with `kotlin-lsp.sh` script
-
-2. Configure [nvim.lsp](https://neovim.io/doc/user/lsp.html) e.g:
-    ```lua
-    {
-      cmd = vim.lsp.rpc.connect('127.0.0.1', tonumber(9999)),
-      single_file_support = true,
-      filetypes = { "kotlin" },
-      root_markers = { "build.gradle", "build.gradle.kts", "pom.xml" },
-    }
-    ```
-   
+1. [Install `kotlin-lsp` CLI](../README.md#install-kotlin-lsp-cli)
+2. Install the official Neovim [`nvim-lspconfig` plugin](https://github.com/neovim/nvim-lspconfig)
+3. Enable the LSP `vim.lsp.enable('kotlin_lsp')`