docs(asset hierarchy): describe the rebuilt hierarchy page

docs/content/asset_modelling/PRO_hierarchy/asset_hierarchy.md

@@ -110,34 +110,44 @@ You can visualize the structure of Assets in DefectDojo, and change relationship
 
 ![image](images/asset_hierarchy.png)
 
-Opening Asset Hierarchy will display a table of all of your Assets which can be filtered.  Selecting one or more Assets from this table will render a hierarchy diagram.
+The page has three parts: a list of your Assets across the top, the diagram below it, and a panel on either side of the diagram. Selecting one or more Assets in the list draws them, and each Asset you select becomes a starting point that the diagram builds around. The list can be filtered, and once you have the Assets you want you can collapse it with the **Hide Asset List** button to give the diagram the whole page.
 
 ![image](images/asset_hierarchy_diagram.png)
 
 ### Diagram navigation
 
-The icons at the top left of the hierarchy diagram allow you to zoom in and out.  Clicking and dragging in this diagram allows you to scroll through the diagram.
+The buttons at the bottom left of the diagram zoom in and out, and fit the whole diagram in view. Clicking and dragging the background moves the diagram, and each Asset can be dragged for display purposes.
 
-Each Asset is rendered as a single node in this diagram, which can be moved around for display purposes.
+Assets are connected by labelled arrows running from parent to child, which represent the kind of relationship each node has to the other. Currently, `parent` is the only label supported.
 
-Assets are connected together using labelled paths, which represent the kind of relationship each note has to one another.  Currently, `parent` is the only label supported.
+Each node is coloured by where it came from: one colour for the Assets you selected in the list, another for Assets the diagram loaded because they are related to your selection. The **Legend** in the left panel names both.
 
-### Exploring Asset nodes
+The left panel also chooses what the nodes display. **Asset ID**, **Organization ID**, **Organization Name** and **Child Count** can each be turned on or off.
 
-Each Asset node can be interacted with by clicking on the blue buttons.  These buttons appear only when an Asset node is selected (by clicking on the node).
+### Acting on an Asset
+
+Clicking an Asset's node selects it, which fills both panels: the left panel lists what you can do with that Asset, and the right panel describes it, including its Organization, its relationship to its parent, how many children it has, and links to its metrics.
 
 ![image](images/asset_hierarchy_node.png)
 
-* 👁️ (eyeball icon) will take you directly to the corresponding Asset View (formerly known as the Product View).
-* ✏️ (pencil icon) will open a modal with the Edit Asset form (formerly known as the Edit Product form)
-* ➕ (plus icon) will allow you to add a new Child Asset to this Asset.  The Asset does not need to be currently visible in the diagram, but must be part of the same Organization.
-* ✥ (four-arrows icon) allows you to change the Parent Asset of the currently selected Asset.
-* 🗑️ (trash can icon) allows you to remove an Asset's parent relationship. This icon only appears if an Asset already has a Parent.
+* **Open Asset** takes you to the corresponding Asset View (formerly known as the Product View).
+* **Edit Asset** opens the Edit Asset form (formerly known as the Edit Product form).
+* **Add Child** nests another Asset under this one. You can choose an Asset that is not currently in the diagram, or create a new one, but either way it must be part of the same Organization.
+* **Change Parent** moves the selected Asset underneath a different parent.
+* **Remove From Hierarchy** detaches the Asset from its parent, and asks whether that Asset's own children should be left without a parent or moved up to the parent you are detaching from. It is only available when the Asset has a parent.
+
+Each of these opens in the right panel, so the diagram stays visible while you work on it. An action you cannot use is shown greyed out, and hovering it explains why: changing relationships needs edit permission on the Asset itself as well as permission to edit the hierarchy.
+
+### Loading more of the hierarchy
 
-If your diagram displays an Asset with un-selected Parent Assets, you can click the Load More button to populate the diagram with the Parent Asset (as well as that Parent Asset's children).
+The diagram loads part of the hierarchy at a time, so a large one stays readable.
+
+Where an Asset's parent has not been loaded, a **Load Parents** button appears above it, which adds that parent along with the parent's other children.
 
 ![image](images/assets_loadmore.png)
 
+Where an Asset has more children than the diagram is currently showing, a **Load** button appears below it, together with a choice of how many to add at a time.
+
 ## Notes
 
 * Note that deduplication scopes have not changed; Assets only deduplicate Findings within themselves, and do not consider Findings in other Assets, regardless of Parent/Child relationships.