feat(Module_Doc): fixup to add property signals

This is a naive approach to automatically add all the `"property::"`
signals. A better way to do that would be to look for this information
in the documentation with the scrapper. It would be, however, less
efficient, and requires quite a few refactors of the data structure.

So this current naive approach will be good enough for now.

src/awesomewm.d.tl/entity/Module_Doc.tl

@@ -56,6 +56,12 @@ local function fixup_static_functions(self: Module_Doc)
    end
 end
 
+local function fixup_properties_signals(self: Module_Doc)
+   for p in self.properties:iter() do
+      self.signals:append("property::" .. p.name)
+   end
+end
+
 local __Module_Doc: metatable<Module_Doc> = {
    __call = function(_: Module_Doc): Module_Doc
       return {
@@ -71,6 +77,7 @@ local __Module_Doc: metatable<Module_Doc> = {
             fixup_methods(self)
             fixup_properties(self)
             fixup_static_functions(self)
+            fixup_properties_signals(self)
          end,
          populate_requires = function(self: Module_Doc)
             -- TODO : Move this to other Entities. Can be a little tricky because we populate a map