Update help.ctp

In line 28
```php
...
$this->Html->link(_d('forum', 'edit profile'),
...
```
is a _ missing before _d.
The correct syntax would be:
```php
...
$this->Html->link(__d('forum', 'edit profile'),
...
```
Merge pull request #57 from jannaahs/patch-1

Update help.ctp