[Unfinished] Document functions

src/stl.h

@@ -146,7 +146,13 @@ typedef struct {
   char          error;            /**< error flag, when something went wrong, this is not 0 */
 } stl_file;
 
+/** Open an STL file and load it's contents
+ * \param stl The struct to load the file data to
+ * \param file Path to the STL file
+ * \warning As IO operation, this could result in an error,
+ * always check the error flag with stl_get_error() or use stl_exit_on_error() after using stl_open() */
 extern void stl_open(stl_file *stl, char *file);
+
 extern void stl_close(stl_file *stl);
 extern void stl_stats_out(stl_file *stl, FILE *file, char *input_file);
 extern void stl_print_edges(stl_file *stl, FILE *file);