feat: adding rockspec

so that one can install the plugin from luarocks.org .
It helps deal automatically with plugin dependencies.

See https://teto.github.io/posts/2022-06-22-neovim-plugin-luarocks-2.html
for more context.

rest.nvim-scm-1.rockspec

@@ -0,0 +1,36 @@
+local MAJOR, REV = "scm", "-1"
+rockspec_format = "3.0"
+package = "rest.nvim"
+version = MAJOR .. REV
+
+description = {
+	summary = "A fast Neovim http client written in Lua",
+	labels = { "neovim", "rest"},
+	detailed = [[
+    rest.nvim makes use of a curl wrapper implemented in pure Lua in plenary.nvim so, in other words, rest.nvim is a curl wrapper so you don't have to leave Neovim!
+   ]],
+	homepage = "https://github.com/rest-nvim/rest.nvim",
+	license = "MIT",
+}
+
+dependencies = {
+	"lua >= 5.1, < 5.4",
+}
+
+source = {
+	url = "http://github.com/rest-nvim/rest.nvim/archive/v" .. MAJOR .. ".zip",
+	dir = "rest.nvim-" .. MAJOR,
+}
+
+if MAJOR == "scm" then
+	source = {
+		url = "git://github.com/rest-nvim/rest.nvim",
+	}
+end
+
+build = {
+   type = "builtin",
+   copy_directories = {
+	   'plugin'
+   }
+}