feat: add superhtml support (#3245)

Co-authored-by: glepnir <glephunter@gmail.com>

lua/lspconfig/server_configurations/superhtml.lua

@@ -0,0 +1,32 @@
+local util = require 'lspconfig.util'
+
+return {
+  default_config = {
+    cmd = { 'superhtml', 'lsp' },
+    filetypes = { 'superhtml', 'html' },
+    root_dir = util.find_git_ancestor,
+    single_file_support = true,
+  },
+  docs = {
+    description = [[
+https://github.com/kristoff-it/superhtml
+
+HTML Language Server & Templating Language Library
+
+This LSP is designed to tightly adhere to the HTML spec as well as enforcing
+some additional rules that ensure HTML clarity.
+
+If you want to disable HTML support for another HTML LSP, add the following
+to your configuration:
+
+```lua
+require'lspconfig'.superhtml.setup {
+  filetypes = { 'superhtml' }
+}
+```
+        ]],
+    default_config = {
+      root_dir = [[util.find_git_ancestor]],
+    },
+  },
+}