Add filters table validation in xdoc folder

[romani]

We need to remove this exclusion of filters from validation

checkstyle/src/test/java/com/puppycrawl/tools/checkstyle/internal/XdocsPagesTest.java

Line 367 in 4aaed8d

|| path.getParent().toString().contains("filters")) {

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

taken from #13270 (comment)