Add a Dapp Frontend as the last step of Getting Started Guide

[janewang]

What problem does your feature solve?

Can't find where is adding a dapp frontend to increment contract

What would you like to see?

Move https://developers.stellar.org/docs/build/apps/dapp-frontend to step 5 of Getting Started guide

[briwylde08]

Hi! So I will explain the reasoning here. When we split the Build tab, we split it between Smart Contracts and Applications. We felt that building a dapp frontend fit better in the Applications section for a user looking for that section specifically.

We do have an Up Next link and pagination that directs users to the dapp frontend guide following the Getting Started section (see screenshot below) to make navigation easier.

Have there been many issues navigating this? I don't think either @ElliotFriend or I are super married to either flow but this made the most sense to us when splitting the content.