Add feature to display welcome message with regex

[RohanVB]

For any message such as hello world!, as long as it contains hello world should prompt the welcome message to be displayed

[sladyn98]

@RohanVB I'm not entirely sure why we would need this :P because we have mentioned in our docs that the message to be posted for help is the wonderful hello world :)

[RohanVB]

Just came across a few users using variations of the expression and thought it'd be useful. People usually explain that they need to type exactly hello world to trigger corobo (including the quotes). Hence the expression with quotes could be removed and everything else containing hello world could be included.

[Vamshi99]

Yes, Hello world! should be allowed. More than one ! also should be allowed.

[sladyn98]

@RohanVB Oh understood 👍
@Vamshi99 Just let me get a few of my PR's merged and will get to discussing this :)