add documentation

gstlal/bin/gstlal_ligo_data_find_check

@@ -16,6 +16,8 @@
 # with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
+## @file
+# A program to check for gaps in frame cache files according to segment lists
 
 #
 # =============================================================================