[Feature request, help wanted] Filter out docs that already have ToCs

[jamesray1]

The simplest way to do this is probably to add an HTML comment in a file like <!--Don't add doctoc, do not remove this line so that a ToC is not automatically added via doctoc--> and then not add a doc if this comment exists in a file.

[louhnmn]

do you think this is solved by this functionality? @jamesray1

ignoring-individual-files