Properly escape "<" and ">" in api-doc documentation.
Since all documentation is rendered via HTML, the characters
"<" and ">" have to be HTML-quoted, otherwise strange things
(omission, unintended renderings) might occur.
E.g. the sentence
Define an interface between a page and an
ADP <include> similar to the page_contract.
was rendered as
Define an interface between a page and an
ADP similar to the page_contract.
which is incorrect.