fix(doc): improve doc generation of types using lpeg

Added a lpeg grammar for LuaCATS and use it in lua2dox.lua

runtime/lua/vim/lsp/util.lua

@@ -790,7 +790,7 @@ end
 --- Note that if the input is of type `MarkupContent` and its kind is `plaintext`,
 --- then the corresponding value is returned without further modifications.
 ---
----@param input (`MarkedString` | `MarkedString[]` | `MarkupContent`)
+---@param input (lsp.MarkedString | lsp.MarkedString[] | lsp.MarkupContent)
 ---@param contents (table|nil) List of strings to extend with converted lines. Defaults to {}.
 ---@return string[] extended with lines of converted markdown.
 ---@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_hover
@@ -2115,8 +2115,8 @@ end
 --- Returns the UTF-32 and UTF-16 offsets for a position in a certain buffer.
 ---
 ---@param buf integer buffer number (0 for current)
----@param row 0-indexed line
----@param col 0-indexed byte offset in line
+---@param row integer 0-indexed line
+---@param col integer 0-indexed byte offset in line
 ---@param offset_encoding string utf-8|utf-16|utf-32 defaults to `offset_encoding` of first client of `buf`
 ---@return integer `offset_encoding` index of the character in line {row} column {col} in buffer {buf}
 function M.character_offset(buf, row, col, offset_encoding)