Small fix for a typo in the regular expression docs. The line of code above this change does not produce the output shown in the docs. With this change the docs will show the correct output for this example of using regex quantifiers.
- Rename regexp.rdoc to exclude from "Pages". This file is for to be
included in the "class Regexp" document, but it also appeared as a
separate page duplicately.
- Fix links on case-sensitive filesystems.
- Fix to use rdoc-ref instead of converted HTML page names.
