"Combing a website" is the act of keeping a site up-to-date and regularly reviewed to detect and correct errors and/or omissions or, in addition, facts and other information that may be out of date.
To comb a website is absolutely necessary to maintain it, so that it remains accurate and useful. Large sites require frequent and intentional "combing" in order to stay current.
Uncombed websites gradually deteriorate content over time. In these days of booming internet content, to comb a website is an absolute necessity for it to remain accurate, useful and appealing with a large audience.