revset: add explanation about the pattern without explicit kind Before this patch, online help of "adds()", "contains()", "filelog()", "file()", "modifies()" and "removes()" predicates doesn't explain about how the pattern without explicit kind like "glob:" is treated, even though each predicates treat it differently: - as "relpath:" by "adds()", "modifies()" and "removes()" - as "glob:" by "file()" - as special by "contains()" and "filelog()" - be relative to cwd, and - match against a file exactly ("relpath:" matches also against a directory) This may confuse users. This patch adds explanation about the pattern without explicit kind to these predicates.