[0.75] Improve internal 'Help' documentation landing page

**Describe the bug**
The help button on the right-bottom corner now links to https://docs.bitshares.org/ which is outdated and does little help.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to 'https://wallet.bitshares.org/'
2. Click on 'HELP'

**Expected behavior**
Open a page, with links to
* in-wallet help document
* Telegram help channel
* Discord help channel
* Forum technical support board
* other docs site e.g. docs.bitshares.org

Open https://wallet.bitshares.org/ and click HELP to trace the current landing-page link. Done means the help page provides links to in-wallet help, Telegram, Discord, the forum technical-support board, and other documentation such as docs.bitshares.org.

Written by the indexing model from the issue text.