Update docs/releases/1.5.txt

In Django 1.5, you can now use your own model as the store for user-related

data. If your project needs a username with more than 30 characters, or if

you want to store usernames in a format other than first name/last name, or

you want to put custom profile information onto your User object, you can

you want to store user's names in a format other than first name/last name,

or you want to put custom profile information onto your User object, you can

now do so.

If you have a third-party reusable application that references the User model,