Add filters table validation in xdoc folder

[romani]

We need to remove this exclusion of filters from validation https://github.com/checkstyle/checkstyle/blob/4aaed8d80fdcb22e11096e06f7308dc151f9ca76/src/test/java/com/puppycrawl/tools/checkstyle/internal/XdocsPagesTest.java#L367

or we need special test method for filters or we need to explain in comment why filter should be out of scope

taken from https://github.com/checkstyle/checkstyle/pull/13270#discussion_r1238129336