feat: add rockspec

nvim-treesitter is a common dependency across Neovim plugins.
Using luarocks may alleviate the need for users to specify their
plugins' dependencies in their plugin manager.
(e.g., vim-plug or packer).

See also:
https://teto.github.io/posts/2021-09-17-neovim-plugin-luarocks.html

NOTE:
If this is merged, a package on www.luarocks.org will need to be
added, which can be done from only one account.
See luarocks/luarocks-site#173.

nvim_treesitter-scm-1.rockspec

@@ -0,0 +1,38 @@
+local _MODREV, _SPECREV = 'scm', '-1'
+
+rockspec_format = "3.0"
+package = 'nvim_treesitter'
+version = _MODREV .. _SPECREV
+
+description = {
+  summary = 'A framework for interacting with tests within NeoVim.',
+  detailed = [[
+    The goal of nvim-treesitter is both to provide a simple and easy way to use the interface 
+    for tree-sitter in Neovim and to provide some basic functionality such as highlighting based on it.
+  ]],
+  homepage = 'https://github.com/nvim-treesitter/nvim-treesitter',
+  license = 'Apache/2.0',
+  labels = { 'neovim', 'tree-sitter', }
+}
+
+dependencies = {
+  'lua == 5.1',
+}
+
+source = {
+  url = 'https://github.com/nvim-treesitter/nvim-treesitter/archive/v' .. _MODREV .. '.zip',
+  dir = 'nvim-treesitter-' .. _MODREV,
+}
+
+if _MODREV == 'scm' then
+  source = {
+    url = 'git://github.com/nvim-treesitter/nvim-treesitter',
+  }
+end
+
+build = {
+  type = 'builtin',
+  copy_directories = {
+    'doc'
+  }
+}