Flesh out 'User Docs' section of index page

As explained in the new admonition at the top of the page, many of this
docs have not yet been written, and therefore have no links. The idea is
to publish this list of the docs we have _and_ the docs we want to have,
such that users can get a sense of everything we want them to know about
Bisq, even though it's not all ready to go yet, and such that
contributors can get a sense of where they can add value by writing
these incomplete docs.

In subsequent commits, the same kind of 'fleshing out' will be done for
the 'Contributor Docs' section of the index page.

index.adoc

@@ -3,15 +3,52 @@
 :sectanchors:
 :docinfo: private
 
+[TIP]
+.Brand new to Bisq?
+====
+Welcome! Start with the <<essentials>>. You'll be up and trading quickly.
+====
+
+[NOTE]
+.These docs are a work in progress (and you can help)
+====
+Docs without hyperlinks haven't been written yet. If you want to write one, <<contributor-checklist#,let us know>>.
+====
+
 == User Docs
 
- * <<intro#, Introduction>> — Learn what Bisq is, why it exists and how it works
- * <<getting-started#, Getting Started>> — Go from zero to trading in 15 minutes
- * <<secure-wallet#, Secure Your Wallet>> — Keep your bitcoin safe
+=== Essentials
+
+ * <<intro#, Introduction>> — _Learn what Bisq is, why it exists and how it works_
+ * <<getting-started#, Getting Started>> — _Download, set up and start trading with Bisq in minutes_
+ * <<secure-wallet#, Secure Your Wallet>> — _Set a password and save your seed words to keep your bitcoin safe_
+ * Backup and Recovery — _Maintain backups to keep your settings and history safe_
+ * Staying Private — _Maximize control over your personal info and trading data_
+ * Trading and Arbitration Rules — _Know what's expected of you and others when trading_
+ * Fees and Security Deposits - _Understand how your bitcoin is used and kept safe when trading_
+ * Support — _Get help from other Bisq users and contributors_
+
+=== Features
+
+ * Payment Methods — _Explore 20+ supported fiat currency payment methods, from Alipay to Zelle_
+ * Altcoins — _Explore 100+ supported cryptocurrencies, tokens and assets_
+
+=== Ecosystem
+
+ * News and Announcements – _Stay informed with the Bisq https://github.com/bisq-network/proposals/issues/20[mailing list], https://twitter.com/bisq_network[Twitter], https://www.youtube.com/c/bisq-network[YouTube], https://www.facebook.com/bisqnetwork/[Facebook], etc_
+ * Media and Press — _Catch up on talks, interviews, podcasts and articles about Bisq_
+ * Chat and Discussion — _Connect with other users on the Bisq https://bisq.community[Forum], https://bisq.network/slack-invite[Slack], https://webchat.freenode.net/?channels=bisq[IRC], https://keybase.io/team/bisq[Keybase], etc_
+ * Charts and Data – _Explore Bisq https://markets.bisq.network[markets], https://bisq.network/volume[global volume],  https://coin.dance/volume/bisq/[regional volume], https://bisq.network/release-stats[release statistics], etc_
+ * Ratings and Reviews — _Read Bisq user experience reports and reviews on sites like https://www.cryptocompare.com/exchanges/bisq/[CryptoCompare]_
+
+=== Incubating Efforts
+
+ * Bisq HTTP API — _Automate trading and interact programmatically with your Bisq node_
+ * Bisq Mobile — _Operate your Bisq node remotely via a web/mobile frontend_
 
 == Contributor Docs
 
- * <<contributor-checklist#, New contributor checklist>>
+ * <<contributor-checklist#, Contributor Checklist>>
  * <<proposals#, Proposals>>
  * <<exchange/howto/list-asset#, How to list an asset>>
  * <<manual-dispute-payout#, How to issue a manual dispute payout>>