Comment the script, fix README

Author: elibarzilay

.github/workflows/sync

@@ -1,5 +1,17 @@
 #!/usr/bin/env bash
 
+# This script implements a two-way mirroring bewteen a GH wiki for a repo `R`
+# (called `DOTREMOTE` below) with a public repo `R-wiki` (intended for external
+# contributions, called `DASHREMOTE` below).  See `sync.yml` for how it is
+# triggered: it is a minimal-ish yaml file that should be added to both sides
+# (`R` and `R-wiki`), with a `push` trigger on `R-wiki` (and optionally a
+# schedule) and a `gollum` trigger on `R`.  The action spec is careful to
+# always checkout `R-wiki` (`DASHREMOTE`) since checking out `R` would be
+# useless.  It then merges in changes in `DOTREMOTE` and pushes the results to
+# both.  Pushing the merged version will trigger an action on the other side,
+# but that would be very quick (both the `merge` and pushing it will be
+# no-ops.)
+
 set -ue
 shopt -s extglob
 

README.md

@@ -1,8 +1,8 @@
 ## The TypeScript wiki
 
-This repo is a mirror of [the TypeScript wiki](https://github.com/Microsoft/TypeScript/wiki).
-Changes on either the wiki or this repo are immediately mirrored to the other side.
-This is done in a GitHub Action [here](.github/workflows/sync.yml), and [another](https://github.com/microsoft/TypeScript/blob/master/.github/workflows/ci.yml) in the TS repo.
+> This repo is a mirror of [the TypeScript wiki](https://github.com/Microsoft/TypeScript/wiki).
+> Changes on either the wiki or this repo are immediately mirrored to the other side.
+> This is done in a GitHub Action [here](.github/workflows/sync.yml), and [another](https://github.com/microsoft/TypeScript/blob/master/.github/workflows/sync-wiki.yml) in the TS repo, and the main work is done by a [`sync` script](.github/workflows/sync).
 
 The wiki root is [Home.md](./Home.md).