Describe the add menu on right-click in the asset panel (#244)

Concepts.md

@@ -83,6 +83,8 @@ of the scene view's icons (see [Scene editing](Scene-editing)) and the collision
 one in the **Assets** panel. The **Assets** panel's `+` creates an asset and opens its tab; its menu lists the types in
 two alphabetical groups, first what can be placed into a scene, then what only lives in the library
 (#43) — the line between them answers the question that follows right after "which type?".
+A right-click on a group heading or on the empty space below the rows opens the same menu (#244);
+a right-click on an asset keeps its own menu.
 Every type has an **icon** of its own, the same wherever the type shows: in the `+` menu, on the
 asset panel's groups, on a document's tab and at the end of a row in **Scene objects** (#176).
 The asset panel **groups by type** (#176): one heading per type that has assets, with its icon and

Development.md

@@ -15,7 +15,7 @@ npm run build        # writes dist/ and regenerates index.html
 php tools/make-user.php <name> <password> [admin|user]        # an account; every tool signs in (see Accounts)
 php tests/php/accounts.test.php                               # the API's account rules, no server needed (CI's gate job)
 php tests/php/snapshots.test.php                              # the snapshot store (#231), the same way
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1452 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1455 editor checks, screenshots in /tmp/gm-e2e-*.png
 GM_STEPS=20 node tools/e2e.mjs                                # or 1-12, or 6,20 — a subset while working on one step
 ./e2e.sh start [GM_STEPS]                                     # the same run detached, see below
 ./e2e.sh status                                               # live progress, or the last run's result