Add missing manual sections to alphasort()/alphasort64().

Change-Id: Ibc9ce4f07364548a6aa007e64cac9b34b904f4dc
diff --git a/libc/include/dirent.h b/libc/include/dirent.h
index 8058cfb..73fa9ac 100644
--- a/libc/include/dirent.h
+++ b/libc/include/dirent.h
@@ -176,13 +176,13 @@
 int dirfd(DIR* _Nonnull __dir);
 
 /**
- * [alphasort](https://man7.org/linux/man-pages/man3/alphasort.3.html) is a
+ * [alphasort(3)](https://man7.org/linux/man-pages/man3/alphasort.3.html) is a
  * comparator for use with scandir() that uses strcoll().
  */
 int alphasort(const struct dirent* _Nonnull * _Nonnull __lhs, const struct dirent* _Nonnull * _Nonnull __rhs);
 
 /**
- * [alphasort64](https://man7.org/linux/man-pages/man3/alphasort.3.html) is a
+ * [alphasort64(3)](https://man7.org/linux/man-pages/man3/alphasort.3.html) is a
  * comparator for use with scandir64() that uses strcmp().
  */
 int alphasort64(const struct dirent64* _Nonnull * _Nonnull __lhs, const struct dirent64* _Nonnull * _Nonnull __rhs);