Best to include the entire call to action in the link. Also, it's OK to be assertive (ie, don't say please).

Split this message into two strings:
```php
return array(
  "admin:pending_upgrades" => "The site has pending upgrades that require your immediate attention.",
  "admin:view_upgrades" => "View pending upgrades.",
)
```
Wrap the link around the entire second string.