Apply grammar/consistency nits to avfilter_graph_add_filter() doxy.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@22842 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavfilter/avfiltergraph.h

@@ -41,8 +41,9 @@ AVFilterContext *avfilter_graph_get_filter(AVFilterGraph *graph, char *name);
 
 /**
  * Adds an existing filter instance to a filter graph.
- * @param graph  The filter graph
- * @param filter The filter to be added
+ *
+ * @param graph  the filter graph
+ * @param filter the filter to be added
  */
 int avfilter_graph_add_filter(AVFilterGraph *graphctx, AVFilterContext *filter);