Add social media badges on index page

[filfreire]

Add social media badges (with links) on index page for:

• Facebook
• Youtube
• Slack
• Email
• Twitter ?

Examples:

1. taken from Pedro Tavares (@ordepdev) blog

2. taken from yegor256.com

Other possible integrations:

• Linkedin group/organization?

[filfreire]

@FabioCB @filipemcarvalho FYI