Add hint on required relogging for SuMo avatar change to take effect

[Dan]

Currently, any user's avatar changes on FXA (https://accounts.firefox.com/settings) are only synced to SuMo once a user reloggs into their Firefox Account on SuMo (https://support.mozilla.org/en-US/users/auth).

In line 31 of the file kitsune/users/jinja2/users/edit_profile.html,
behind the sentence "To change your email or avatar, visit the Firefox Accounts page.", a hint like
"After an avatar-change, a re-login on support.mozilla.org is required for the changes to be applied." or similar should be added for clarification for SuMo users.

So that both the "My profile" and "Edit my profile" pages should ideally look sth. like this:

Please make the necessary change to Line 31-32 in the file kitsune/users/jinja2/users/edit_profile.html. Thanks.