Add Pin Files page/section to Getting Started section which shows how to pin a file using Web3.storage

[ElPaisano]

As a next step after the reorg currently in progress #1405, add Pin Files page/section to Getting Started section which shows how to pin a file using Web3.storage

Todo: Figure out

• what content lives in this new page/section
• should this be a page or a section with multiple pages
• what are the goal(s) of this page / section i.e. how does it help the reader / what problem does it solve?

[ElPaisano]

@2color created this issue as discussed, lmk if this is accurate