fixes #22378 by changing \d to [0-9]+ in all docs/ and tests/

https://code.djangoproject.com/ticket/22378

As per tomwys' suggestion I changed the regular expressions in the docs and tests from `\d+` to `[0-9]+` in order to get around new issues created by unicode. I didn't change the docs specific to older versions of django because the older docs will still have `\d+`. I changed all expressions rather than just the ones concerning urls for consistency.