Points to an .html file which is included on the gitweb project
overview page ('projects_list' view), if it exists. Relative to
gitweb.cgi script. [Default: indextext.html]
+ * GITWEB_SITE_HTML_HEAD_STRING
+ html snippet to include in the <head> section of each page. [No default]
* GITWEB_SITE_HEADER
Filename of html text to include at top of each page. Relative to
gitweb.cgi script. [No default]