doc: patch-id: emphasize multi-patch processing

Emphasize that you can pass multiple patches or diffs to this command. git-patch-id(1) is an efficient pID–commit mapper, able to map thousands of commits in seconds. But discussions on the command seem to typically[1] use the standard loop-over-rev-list-and- shell-out pattern: for commit in rev-list: prepare a diff from commit | git patch-id This is unnecessary; we can bulk-process the patches: git rev-list --no-merges <ref> | git diff-tree --patch --stdin | git patch-id --stable The first version (translated to shell) takes a little over nine minutes for a commit history of about 78K commits.[2] The other one, by contrast, takes slightly less than a minute. Also drop “the” from “standard input”. † 1: https://stackoverflow.com/a/19758159 † 2: This is `master` of this repository on 2025-10-02 Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name> Signed-off-by: Junio C Hamano <gitster@pobox.com>