docs: [Revert] Improved description of "package" attribute

(manifest).

Per discussion with ddougherty@, decided that this was a high-risk,
low-reward change. Have "undone" the change with the given
"Original-Change-Id" as a result.

Bug: 2735276
Change-Id: I1f6089a1319180aed7d6fdbcf182c5fbe4b49abb
Original-Change-Id: Ifa30615c1cca5f6f19e4d1d0c071e4e256b3151b