Move the document parser inside text_element_parser.

This is to put the context-sensitive parsers together during this early development stage.

src/parser/mod.rs

@@ -2,4 +2,4 @@ mod nom_context;
 mod parser_with_context;
 mod text;
 mod text_element_parser;
-pub use text::document;
+pub use text_element_parser::document;