Add docs for new datastore endpoints

docs/admin.md

@@ -4,7 +4,7 @@ All the API calls here require your user ID to be listed in the configuration as
 
 ## Remote media purge
 
-URL: `POST /_matrix/media/r0/admin/purge_remote?before_ts=1234567890&access_token=your_access_token` (`before_ts` is in milliseconds)
+URL: `POST /_matrix/media/unstable/admin/purge_remote?before_ts=1234567890&access_token=your_access_token` (`before_ts` is in milliseconds)
 
 This will delete remote media from the file store that was downloaded before the timestamp specified. If the file is referenced by newer remote media or local files to any of the configured homeservers, it will not be deleted. Be aware that removing a homeserver from the config will cause it to be considered a remote server, and therefore the media may be deleted.
 
@@ -12,7 +12,7 @@ Any remote media that is deleted and requested by a user will be downloaded agai
 
 ## Quarantine media
 
-URL: `POST /_matrix/media/r0/admin/quarantine/<server>/<media id>?access_token=your_access_token`
+URL: `POST /_matrix/media/unstable/admin/quarantine/<server>/<media id>?access_token=your_access_token`
 
 The `<server>` and `<media id>` can be retrieved from an MXC URI (`mxc://<server>/<media id>`).
 
@@ -23,3 +23,63 @@ Remote media that has been quarantined will not be purged either. This is so tha
 Quarantining media will also quarantine any media with the same file hash.
 
 This API is unique in that it can allow administrators of configured homeservers to quarantine media on their homeserver only. This will not allow local administrators to quarantine remote media or media on other homeservers though, just on theirs.
+
+## Datastore management
+
+Datastores are used by the media repository to put files. Typically these match what is configured in the config file, such as s3 and directories. 
+
+#### Listing available datastores
+
+URL: `GET /_matrix/media/unstable/admin/datastores?access_token=your_access_token`
+
+The result will be something like: 
+```json
+{
+  "00be9363007feb66de554a79e16b7b49": {
+    "type": "file",
+    "uri": "/mnt/media"
+  },
+  "2e17bad1bf76c9618e3cde30166dc674": {
+    "type": "s3",
+    "uri": "s3:\/\/example.org\/bucket-name"
+  }
+}
+```
+
+In the above response, `00be9363007feb66de554a79e16b7b49` and `2e17bad1bf76c9618e3cde30166dc674` are datastore IDs.
+
+#### Estimating size of a datastore
+
+URL: `GET /_matrix/media/unstable/admin/datastores/<datastore id>/size_estimate?access_token=your_access_token`
+
+Sample response:
+```json
+{
+  "thumbnails_affected": 672,
+  "thumbnail_hashes_affected": 598,
+  "thumbnail_bytes": 49087657,
+  "media_affected": 372,
+  "media_hashes_affected": 346,
+  "media_bytes": 340907359,
+  "total_hashes_affected": 779,
+  "total_bytes": 366601489
+}
+```
+
+#### Transferring media between datastores
+
+URL: `POST /_matrix/media/unstable/admin/datastores/<source datastore id>/transfer_to/<destination datastore id>?access_token=your_access_token`
+
+The response is the estimated amount of data being transferred:
+```json
+{
+  "thumbnails_affected": 672,
+  "thumbnail_hashes_affected": 598,
+  "thumbnail_bytes": 49087657,
+  "media_affected": 372,
+  "media_hashes_affected": 346,
+  "media_bytes": 340907359,
+  "total_hashes_affected": 779,
+  "total_bytes": 366601489
+}
+```