docs: update to new link name

Author: voxpelli

docs/index.md

@@ -1296,7 +1296,7 @@ In parallel mode, Mocha does not guarantee the order in which test files will ru
 
 Because of this, the following options, which depend on order, _cannot be used_ in parallel mode:
 
-- [`--file`](#-file-filedirectoryglob)
+- [`--file`](#-file-file)
 - [`--sort`](#-sort-s)
 - [`--delay`](#delayed-root-suite)
   {:.single-column}