Issue found on page 'Keywords and Identifiers': remove sections on string literals and numeric literals

[rpbouman]

This page is about keywords and identifiers, but also contains two sections about literals, https://duckdb.org/docs/sql/keywords_and_identifiers#string-literals and https://duckdb.org/docs/sql/keywords_and_identifiers#numeric-literals.

I think these sections should not be here, whatever information they have should probably be moved to https://duckdb.org/docs/sql/data_types/literal_types

Page URL: https://duckdb.org/docs/sql/keywords_and_identifiers.html