Add help text register page

[Lissyvn]

Recently, I have been contacted by several persons who did not succeed to register as a RSR user. I found out that this is because they entered spaces into their username and did not get an error for this, it just gives a general error.
Can we include a help text that it is not allowed to enter spaces in your username?
I'm talking about this page: http://rsr.akvo.org/accounts/register2/?org_id=42

[kardan]

[kardan]

Updated the error message from only saying "Enter a valid value" with the additional texts below. Didn't not type anything particular about spaces, we could do that but then there is a lot of other characters you are not allowed to use.

[adriancollier]

This looks good to me 😄

[Lissyvn]

+1!

[rumca]

Works as intended on UAT.

Might be a good idea to explicitly state no spaces allowed in the error message?

[adriancollier]

We thought about this - but if we specifically mention spaces, we should probably list all the other restricted characters, and that could get messy. I think a message that is positive (mentions allowed) is nicer 😄