Fix capitalization in L<...> so links work in HTML.

The in-page link to "Component Base Classes" subheading doesn't work on both search.cpan.org and metacpan.org under the Attributes section.

This is because HTML anchors are apparently case sensitive.

See http://search.cpan.org/~ether/Catalyst-Manual-5.9007/lib/Catalyst/Manual/ExtendingCatalyst.pod#Attributes and try to click on the link at the end of "...Catalyst encounters them by providing your own component base class."