docs(hierarchy): the package doc names every key an alias reaches

it described the alias table as it stood before the label and test-tag
names reached the keys android and web write, and said nothing about
expansion being one level deep, which is why each name has to list every
key rather than hop through another alias.

internal/hierarchy/hierarchy.go

@@ -19,11 +19,14 @@
 //	Path queries (global scan only, string form):
 //	  <sel> > <sel> > ...  - each segment matched within subtree of previous match
 //
-// Cross-platform aliases are expanded automatically: "label" / "accessibilityLabel"
+// Cross-platform aliases are expanded automatically, one level deep: every name
-// resolve to accessibilityText; "content-desc" also checks accessibilityText and
+// for a fact lists every key a producer writes it under rather than hopping
-// vice-versa; "identifier" / "accessibilityIdentifier" / "testTag" resolve to
+// through another alias. "label" / "accessibilityLabel" / "ariaLabel" /
-// resource-id (and to each other) so a Compose testTag matches whether the
+// "contentDescription" resolve to accessibilityText and content-desc, which also
-// underlying platform exposes it as resource-id (Android) or accessibilityIdentifier (iOS).
+// check each other; "identifier" / "accessibilityIdentifier" / "testTag" /
+// "testID" resolve to resource-id, to each other and to data-testid, so a
+// Compose testTag matches whether the platform exposes it as resource-id
+// (Android), accessibilityIdentifier (iOS) or data-testid (web).
 package hierarchy
 
 import (