[4.2.x] Fixed typo in docs/topics/auth/passwords.txt.

Wrapped hashing is only possible if the inner wrapped function is the
same as the previous hasher.
Backport of 0265b1b49b from main

docs/topics/auth/passwords.txt

@@ -336,7 +336,7 @@ to happen when a user logs in (which may never happen if a user doesn't return
 to your site). In this case, you can use a "wrapped" password hasher.
 
 For this example, we'll migrate a collection of MD5 hashes to use
-PBKDF2(SHA1(password)) and add the corresponding password hasher for checking
+PBKDF2(MD5(password)) and add the corresponding password hasher for checking
 if a user entered the correct password on login. We assume we're using the
 built-in ``User`` model and that our project has an ``accounts`` app. You can
 modify the pattern to work with any algorithm or with a custom user model.