Expand on UI description.

* What you'll see if EDMC can't determine current Commander.
 * What the various "status on EDSM" icons mean after current system
   name.
 * Correct link to 'New-user-guide' (.md on the end breaks it to go to
   'raw' version).
 * Other misc typo fixes and clean-ups.

Home.md

@@ -32,35 +32,82 @@ PS4 and Xbox are not supported.
 # Usage
 
 Start the application before entering the game to ensure that you don't miss any
-data - some data is only available at game start.
+data.
 
-However you will need your most recent game session to have included
-logging all the way into the game in order to set up some of this
-applications options.  See
+## Caveat on starting EDMC first
+However, *if your most recent game session didn't include you logging
+all the way into the game* then:
+
+ * No 'Cmdr' name will be displayed - the application doesn't yet
+ know this.  EDMC has multi-account/commander support, and doesn't
+ assume it should use the last Commander.
+ * No 'Ship' name will be displayed.
+ * No 'System' name will be displayed.
+ * No 'Station' name will displayed.
+ * You might not be able to click the 'Update' button.
+
+This can also be caused by a corrupt or incomplete most recent Journal
+file.
+
+If the 'Update' button is clickable then using it will fetch the latest
+data from the Frontier CAPI and the fields mentioned above should be
+filled in.
+
+See
 [Troubleshooting - Credentials settings are greyed out](Troubleshooting#credentials-settings-are-greyed-out)
 
+---
+
 The user-interface is deliberately minimal - your choice of data is automatically downloaded, transmitted and/or saved when you start Elite: Dangerous, land at a station, jump to a system or scan a body. 
 
 
 ## Ship Name
-Click on the ship name to view its loadout on [E:D Shipyard](https://edsy.org) (“EDSY”) or [Coriolis](https://coriolis.io) in your web browser.
+Click on the ship name to view its loadout on your chosen 'Shipyard'
+provider ([E:D Shipyard](https://edsy.org) (“EDSY”) or [Coriolis](https://coriolis.io)) in your web browser.
+
+ * Change which provider you use on 'File' > 'Settings' >
+ 'Configuration' (tab) > 'Preferred websites' > 'Shipyard'.
 
 ## System name
 Click on the system name to view its entry in [Elite: Dangerous Database](https://eddb.io/) (“eddb”), [Elite Dangerous Star Map](https://www.edsm.net/) (“EDSM”) or [Inara](https://inara.cz) in your web browser.
 
+ * Change which provider you use on 'File' > 'Settings' >
+ 'Configuration' (tab) > 'Preferred websites' > 'System'.
+ * If your selected provider doesn't yet have data for the system in
+ question then mouse-over will show a 'stop sign' icon.
+ * Whether you use EDSM as the provider or not you might see an extra
+ image at the end of the System name:
+ 	1. <Green Circle> - This system is known to EDSM,
+	   including co-ordinates.
+	1. <Red Circle> - This system is *not* known to EDSM.
+	1. <Yellow Star> - You were the first to report this
+	   system to EDSM.
+	1. <?> - An error occurred checking the status of the
+	   system on EDSM.
+
 ## Station name
 Click on the station name to view its entry in [eddb](https://eddb.io/), [EDSM](https://www.edsm.net/) or [Inara](https://inara.cz) in your web browser.
 
-NB: This only works whilst docked.  You might see an `×`
-character as the name sometimes when not docked.  This means the application
-has determined that you're in a populated system and clicking this `×`
-will open the *system* page so you can see a listing of stations in it.
+ * Change which provider you use on 'File' > 'Settings' >
+ 'Configuration' (tab) > 'Preferred websites' > 'Station'.
+ * This only works whilst docked.  You might see an `×`
+ character as the name sometimes when not docked.  This means the
+ application has determined that you are in a populated system and
+ clicking this `×` will open the *system* page so you can see a listing
+ of stations in the current system.
+ * Similarly to the 'System' name, this might not be clickable if your
+ chosen 'Station' provider doesn't have data for the station in question.
+ You'll see the 'stop sign' icon on mouseover if this is the case.
 
 ## Update button
 
-*Remember, the application will automatically respond to game data so as
-to udpate and/or send it as needed*.  Under normal circumstances you
-won't ever need to press this button.
+This button will not be available until
+[Frontier Authentication](Troubleshooting#problems-with-frontier-authentication)
+is completed for the currently active Commander.
+
+**Remember, the application will automatically respond to game data so as
+to update and/or send it as needed**.  *Under normal circumstances you
+won't ever need to press this button.*
 
 But if, for instance, you've been docked in a station for 15 minutes and
 want to ensure that EDDB etc have the latest commodities information
@@ -71,13 +118,13 @@ over-tax the Frontier CAPI service. The text 'Update' will change to
 'cooldown XXs' during this cooldown.
 
 Plugins might have their own internal cooldowns or queues which
-cause pressing this button to not necessarily send/update data.
+cause pressing this button to not necessarily send/update data,
+immediately or at all.
 
 ## Bottom status line
 
-The bottom-most line of stock EDMC (no extra plugins), just below the
-'Update' button, is used for short messages conveying status
-information and/or errors.
+The bottom-most line of EDMC, just below the 'Update' button, is used
+for short messages conveying status information and/or errors.
 
 ## Log file
 
@@ -98,7 +145,7 @@ See also [Troubleshooting](Troubleshooting.md)
 # Miscellaneous
 To get started with the application see
 [Installation & Setup](Installation-&-Setup)
-and [New user guide](New-user-guide.md).
+and [New user guide](New-user-guide).
 
 Support is available in the #edmc channel of the
 [![Discord chat](https://img.shields.io/discord/164411426939600896.svg?style=social&label=Discord%20chat)](https://discord.gg/usQ5e6n)