[docs] Add onMakeDirectory and onMakeSymlink to the list of tracking delegates (emscripten-core#27326)

This is to match the example code below that list, which contains
onMakeDirectory and onMakeSymlink, while they are absent from the list
above.

Reading only the list and not the example code below it, I was confused
about how to track directory creation, and this pull request should
resolve that confusion for others.

Author: WebCoder49

site/source/docs/api_reference/Filesystem-API.rst

@@ -883,6 +883,8 @@ File system API
   - ``onReadFile`` — Indicates file is being read and number of bytes read.
   - ``onSeekFile`` — Indicates seeking within a file, position, and whence.
   - ``onCloseFile`` — Indicates a file being closed.
+  - ``onMakeDirectory`` — Indicates a directory being created.
+  - ``onMakeSymlink`` — Indicates a symlink (symbolic link) being created.
 
   :callback name: The name of the callback that indicates the filesystem event