Document return value for git_libgit2_features
diff --git a/include/git2/common.h b/include/git2/common.h
index d62d9be..c421d3c 100644
--- a/include/git2/common.h
+++ b/include/git2/common.h
@@ -167,6 +167,9 @@ typedef enum {
* - GIT_FEATURE_SSH
* Libgit2 supports the SSH protocol for network operations. This requires
* the libssh2 library to be found when compiling libgit2
+ *
+ * - GIT_FEATURE_NSEC
+ * Libgit2 supports the sub-second resolution in file modification times.
*/
GIT_EXTERN(int) git_libgit2_features(void);