/usr/bin/gtkdoc-check
/usr/bin/gtkdoc-depscan
/usr/bin/gtkdoc-fixxref
/usr/bin/gtkdocize
/usr/bin/gtkdoc-mkdb
/usr/bin/gtkdoc-mkhtml
/usr/bin/gtkdoc-mkman
/usr/bin/gtkdoc-mktmpl
/usr/bin/gtkdoc-rebase
/usr/bin/gtkdoc-scan
/usr/bin/gtkdoc-scangobj
/usr/bin/gtkdoc-scanobj
You may install this package on CentOS with
yum
install gtk-doc