Rename 6.1_buildconf to 6.1_buildconf.md

Author: Thefrank

6.1_buildconf renamed to 6.1_buildconf.md

@@ -49,4 +49,4 @@ Test failures (if any):
  Use of av_clip() where av_clip_uintp2() could be used:
  Use of av_clip() where av_clip_intp2() could be used:
 Test source failed. Look at tests/data/fate/source.err for details.
-```
+```