docs(treesitter): expose LanguageTree:parent() #32108

Plugins may want to climb up the LanguageTree.

Also add missing type annotations for other methods.

runtime/lua/vim/treesitter/languagetree.lua

@@ -267,6 +267,7 @@ function LanguageTree:trees()
 end
 
 --- Gets the language of this tree node.
+--- @return string
 function LanguageTree:lang()
   return self._lang
 end
@@ -307,11 +308,13 @@ function LanguageTree:is_valid(exclude_children)
 end
 
 --- Returns a map of language to child tree.
+--- @return table<string,vim.treesitter.LanguageTree>
 function LanguageTree:children()
   return self._children
 end
 
 --- Returns the source content of the language tree (bufnr or string).
+--- @return integer|string
 function LanguageTree:source()
   return self._source
 end
@@ -630,7 +633,8 @@ function LanguageTree:add_child(lang)
   return self._children[lang]
 end
 
---- @package
+---Returns the parent tree. `nil` for the root tree.
+---@return vim.treesitter.LanguageTree?
 function LanguageTree:parent()
   return self._parent
 end