gitweb: Describe CSSMIN and JSMIN in gitweb/INSTALL
gitweb: Describe CSSMIN and JSMIN in gitweb/INSTALL

The build-time configuration variables JSMIN and CSSMIN were mentioned
only in Makefile; add their description to gitweb/INSTALL.

This required moving description of GITWEB_JS up, near GITWEB_CSS and
just introduced CSMIN and JSMIN.

Signed-off-by: Jakub Narebski <a6a1517a087f9f64a72f41a0de57ff01fbb0e412@gmail.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git