Fix misleading FAQ entries

During translation of phpBB 3.1 I found a few possible issues in en/help_faq.php:

This allows you to save passages to be completed and submitted at a later date. To reload a saved passage, visit the User Control Panel.

Shouldn't there be message (2x)?

You can block a user from sending you private messages by using message rules within your User Control Panel....

In message rules is not option to block the user from sending you PMs, but option to automatically delete PMs from users. In the end it is the same, but I think in FAQ it should be corrected.

...You can also add a signature by default to all your posts by checking the appropriate radio button in your profile...

It's actually in UCP - Board Preferences - Edit posting defaults

... Please do not abuse the board by posting unnecessarily just to increase your rank. Most boards will not tolerate this and the moderator or administrator will simply lower your post count.

I don't think there is in phpBB such a function. At least I didn't find it.