Add a design showcase on landing

[kartikcho]

Addition to #242, I came up with an idea and some mocks for the new landing page section as discussed in this thread, check it out for more context.

The web view with 3 monthly designs to showcase

Although the mock shows 6, the discussed upon addition will have 3 cards and a link to Design Archive where earlier posts would be available.

For smaller viewports

Layout design ideas

Came up with a few possible layouts for displaying an image while experimenting with Bootstrap 4. We're going with the 2nd card design as decided on the thread.

Expected deliverables from this issue,

• 3 horizontal cards with a link to a new archive page (maybe adding a new page could be split into a different PR).
• 1-1 design of bootstrap card in the mock above
• The name label, if empty, says ‘OSD community member’ to respect privacy of those who would not like to be named.
• If the new page is being worked upon, it should follow a layout similar to the first mock and extend to infinity and beyond🚀

[kartikcho]

Assigned to @Erioldoesdesign, let me know if you need any help!