m.room.history_visibility/README.md: initial commit

matrix/m.room.history_visibility/README.md

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+# `m.room.history_visibility`
+
+`m.room.history_visibility` controls who can view the room history.
+
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+
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+
+- [Example](#example)
+- [Options](#options)
+- [See also](#see-also)
+
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+
+## Example
+
+```json
+{
+  "history_visibility": "invited"
+}
+```
+
+## Options
+
+[Refer to the upstream for canonical information.](https://spec.matrix.org/latest/client-server-api/#room-history-visibility)
+
+- `world_readable` - anyone can read the history without joining, and it
+  likely will be indexed by search engines.
+- `shared` - history is shared to all users in the room, regardless of when
+  they joined.
+  - [Matrix public archive will publish history of rooms with this option although not allow search engines to index.](https://github.com/matrix-org/matrix-public-archive/blob/main/docs/faq.md#why-does-the-archive-user-join-rooms-instead-of-browsing-them-as-a-guest)
+- `invited` - users can see history from the point of time they were invited
+  to the room. **_RECOMMENDED FOR SEMI-PUBLIC ROOMS_**
+- `joined` users can see history from the point of time they joined
+
+**_WARNING!_** Changing the option **will not affect old messages**.
+
+## See also
+
+- `m.room.join_rules`