doc: fix a typo in permissions.md

Signed-off-by: Daeyeon Jeong <daeyeon.dev@gmail.com>
PR-URL: nodejs#47730
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Debadree Chatterjee <debadree333@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/permissions.md

@@ -536,7 +536,7 @@ Example:
 
 Wildcards are supported too:
 
-* `--allow-fs-read:/home/test*` will allow read access to everything
+* `--allow-fs-read=/home/test*` will allow read access to everything
   that matches the wildcard. e.g: `/home/test/file1` or `/home/test2`
 
 There are constraints you need to know before using this system: