Add more documentation for customselector
Add more documentation for customselector

Fix #137
filamentgroup/grunticon,aoimedia/grunticon,bluespore/grunticon,danigirl329/grunticon,ebsco/grunticon,filamentgroup/grunticon,ebsco/grunticon,bluespore/grunticon,aoimedia/grunticon,danigirl329/grunticon