Add documentation for setting up a token

bot/src/main/java/com/dongtronic/diabot/platforms/discord/commands/nightscout/NightscoutCommand.kt

@@ -53,7 +53,7 @@ class NightscoutCommand(category: Category) : DiscordCommand(category, null) {
         this.guildOnly = false
         this.aliases = arrayOf("ns", "bg", "bs")
         this.examples = arrayOf(
-            "diabot nightscout casscout", "diabot ns", "diabot ns set https://casscout.herokuapp.com",
+                "diabot nightscout casscout", "diabot ns", "diabot ns set https://casscout.herokuapp.com",
                 "diabot ns @SomeUser#1234", "diabot ns public false"
         )
         this.children = arrayOf(
@@ -446,7 +446,7 @@ class NightscoutCommand(category: Category) : DiscordCommand(category, null) {
                     }
                 }
 
-                is UnconfiguredNightscoutException -> "Please set your Nightscout hostname using `diabot nightscout set <hostname>`"
+                is UnconfiguredNightscoutException -> "Please set your Nightscout hostname using `/nightscout set url <hostname>`"
                 is IllegalArgumentException -> "Error: ${ex.message}"
                 is InsufficientPermissionException -> {
                     logger.info("Couldn't reply with nightscout data due to missing permission: ${ex.permission}")
@@ -492,7 +492,8 @@ class NightscoutCommand(category: Category) : DiscordCommand(category, null) {
                 is HttpException -> {
                     if (ex.code() == 401) {
                         message += if (userDTO.jdaUser != null && userDTO.jdaUser == author) {
-                            "Could not authenticate to Nightscout. Please set an authentication token with `diabot nightscout token <token>`"
+                            "Could not authenticate to Nightscout. Please set an authentication token with `/nightscout set token <token>`, " +
+                                    "or view our [setup guide](https://github.com/discord-diabetes/diabot/blob/main/docs/nightscout_setup.md)."
                         } else {
                             "Nightscout data is unreadable due to missing token."
                         }

docs/nightscout_setup.md

@@ -0,0 +1,45 @@
+# Nightscout tokens and Diabot
+
+If your Nightscout instance is running
+in [token authentication mode](https://nightscout.github.io/nightscout/security/#how-to-turn-off-unauthorized-access), and you want to use
+the Nightscout features of the bot, you'll need to set an access token so Diabot access and read your Nightscout data.
+You can read more about creating a token [here](https://nightscout.github.io/nightscout/security/#create-authentication-tokens-for-users)
+
+## Quick Guide
+
+1. Starting at your Nightscout page, click the 3 horizontal lines in top right -> "Admin Tools"
+2. Click "Add new Subject". Put anything for name (e.g. `diabot`) and put `readable` for roles. Click "Save" in the bottom left.
+3. In the "Access Token" column, right-click on the diabot token you just created and copy the link.
+4. In Discord, type `/nightscout set url` and click on the command that appears above the chat box. Paste the link you just copied into
+   the `url` input field for that command. Send the command.
+5. Run `diabot ns` in the chat to confirm it's working.
+
+## Regular Guide
+
+1. Open your Nightscout page. In the top right, click on the 3 horizontal lines, and click "Admin Tools"
+
+   ![Picture showing the location of the admin tools link](./images/token/step_1.png?raw=true)
+
+2. Once in the admin tools page, click "Add new Subject" which will open a menu.
+
+   ![Picture of the "Add new Subject" button](./images/token/step_2.png?raw=true)
+
+3. You can put anything for the name, but in this example we'll use `diabot`. For the roles, put in `readable`. Once you've confirmed the
+   values look correct, click "Save" in the bottom-left of the menu.
+
+   ![Picture showing an example of how the subject fields should look](./images/token/step_3.png?raw=true)
+
+4. After saving it, the new Diabot subject should appear in the table. You can see the new token under the "Access Token" column; it'll
+   appear as a link to your Nightscout with the token filled in. Right-click on the token link and copy it to your clipboard.
+
+   ![Picture of the access token link](./images/token/step_4.png?raw=true)
+
+5. Go over to Discord. Make sure you're in a server with Diabot in it. In the chat box, type `/nightscout set url` and click on the command
+   that appears above the chat box. Your cursor should be in a command option/field box now. Paste the link we copied in step 4 into the
+   box.
+
+   ![Picture of the command to select](./images/token/step_5-1.png?raw=true)
+   ![Picture of the command with the URL option filled out](./images/token/step_5-2.png?raw=true)
+
+6. Once you have the link in the command field as shown above, send the command by hitting enter or clicking on the send button. Diabot
+   should update your URL and you can now test to make sure it works by running `diabot ns`.