update readmes + fix typo

bin/hooks/README.md

@@ -2,15 +2,24 @@ standalone programs which are executed by copyparty when an event happens (uploa
 
 these programs either take zero arguments, or a filepath (the affected file), or a json message with filepath + additional info
 
+run copyparty with `--help-hooks` for usage details / hook type explanations (xbu/xau/xiu/xbr/xar/xbd/xad)
+
 > **note:** in addition to event hooks (the stuff described here), copyparty has another api to run your programs/scripts while providing way more information such as audio tags / video codecs / etc and optionally daisychaining data between scripts in a processing pipeline; if that's what you want then see [mtp plugins](../mtag/) instead
 
 
 # after upload
 * [notify.py](notify.py) shows a desktop notification ([example](https://user-images.githubusercontent.com/241032/215335767-9c91ed24-d36e-4b6b-9766-fb95d12d163f.png))
+  * [notify2.py](notify2.py) uses the json API to show more context
 * [discord-announce.py](discord-announce.py) announces new uploads on discord using webhooks ([example](https://user-images.githubusercontent.com/241032/215304439-1c1cb3c8-ec6f-4c17-9f27-81f969b1811a.png))
 * [reject-mimetype.py](reject-mimetype.py) rejects uploads unless the mimetype is acceptable
 
 
+# upload batches
+these are `--xiu` hooks; unlike `xbu` and `xau` (which get executed on every single file), `xiu` hooks are given a list of recent uploads on STDIN after the server has gone idle for N seconds, reducing server load + providing more context
+* [xiu.py](xiu.py) is a "minimal" example showing a list of filenames + total filesize
+* [xiu-sha.py](xiu-sha.py) produces a sha512 checksum list in the volume root
+
+
 # before upload
 * [reject-extension.py](reject-extension.py) rejects uploads if they match a list of file extensions