feat: add fsharp-language-server (neovim#2186)

lua/lspconfig/server_configurations/fsharp_language_server.lua

@@ -0,0 +1,29 @@
+local util = require 'lspconfig.util'
+
+return {
+  default_config = {
+    cmd = { 'dotnet', 'FSharpLanguageServer.dll' },
+    root_dir = util.root_pattern('*.sln', '*.fsproj', '.git'),
+    filetypes = { 'fsharp' },
+    init_options = {
+      AutomaticWorkspaceInit = true,
+    },
+    settings = {},
+  },
+  docs = {
+    description = [[
+F# Language Server
+https://github.com/faldor20/fsharp-language-server
+
+An implementation of the language server protocol using the F# Compiler Service.
+
+Build the project from source and override the command path to location of DLL.
+
+If filetype determination is not already performed by an available plugin ([PhilT/vim-fsharp](https://github.com/PhilT/vim-fsharp), [fsharp/vim-fsharp](https://github.com/fsharp/vim-fsharp), and [adelarsq/neofsharp.vim](https://github.com/adelarsq/neofsharp.vim).
+), then the following must be added to initialization configuration:
+
+
+`autocmd BufNewFile,BufRead *.fs,*.fsx,*.fsi set filetype=fsharp`
+]],
+  },
+}