Include description of FH on front page, right above list of FH events this semester

[staceytay]

I propose putting a simple description of FH to

• indicate that it's open to everyone
• tell readers how to contact us if they'd like to speak.

This is primarily to reduce the number of emails we get asking us if talks are open to non-NUS students or if they'd need to register to attend.

Sample Description Friday Hacks is our weekly gathering where we invite students and speakers from academia and industry to give technical talks. Anyone, even non-NUS students are welcome to attend, just show up on the day itself! If you'd like to speak, find out more on how to contact us and what to include in your message. See you at our next Friday Hacks!

[ngzhian]

I like your description, slightly on the long side, how about:

Anyone, even non-NUS students are welcome to attend, our weekly Friday hacks. Want to speak, or wish to find out more? <link to a subsection on a page where we give more details about FH, like FAQ>

[yyjhao]

pull request + screenshot plz