website/docs: add flow inspector docs

closes #2105

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

website/docs/flow/inspector.md

@@ -0,0 +1,33 @@
+---
+title: Inspector
+---
+
+The flow inspector, introduced in 2021.10, allows administrators to easily figure out how custom flows work, inspect the current context and debug issues.
+
+:::info
+When running a flow with the inspector enabled, the flow is still executed normally. This means that for example, a `user_write` stage will _actually_ write user data.
+:::
+
+![](./inspector.png)
+
+The following infos are shown in the inspector
+
+## Next stage
+
+This is the currently planned next stage. If you have stage bindings configured to evaluate on plan (default), then you will see the result here. If you however have them configured to re-evaluate, then this will not show up here, since the results will vary based on your input.
+
+Shown is the name and kind of the stage, as well as the unique ID.
+
+## Plan history
+
+Here you can see an overview of which stages have run, which is currently active, and which is planned to come next. Same caveats as above apply.
+
+## Current plan context
+
+This shows you the current context. This will contain fields depending on the same, after an identification stage for example you would see "pending_user" be set.
+
+This data is not cleaned, so if your flow involves inputting a password, it will be shown here too.
+
+## Session ID
+
+The unique ID for the currently used session. This can be used to debug issues with flows restarting/loosing state.

website/sidebars.js

@@ -75,7 +75,7 @@ module.exports = {
         {
             type: "category",
             label: "Flows",
-            items: ["flow/index", "flow/examples"],
+            items: ["flow/index", "flow/inspector", "flow/examples"],
         },
         {
             type: "category",