add json instructions, drop export from git

README.md

@@ -1,6 +1,25 @@
 Static HTML page with the libregaming matrix spaces
 The HTML is generated with script.py using the spaces json
 
+# Update libregamingspaces.json
+
+Get server baseurl and Access Token from your client e.g. Element -> All settings -> Help & About -> Advanced
+
+```
+SERVER=
+TOKEN=
+SPACE='!IdUUdKALNzBLKEjvbP:matrix.org'
+
+URL="$SERVER/_matrix/client/v1/rooms/$SPACE/hierarchy?access_token=$TOKEN"
+# first call can take about 30s
+FROM=$(curl "$URL" | tee -a hierarchy.json | jq -r .next_batch); echo $FROM
+# repeat pagination until "null"
+FROM=$(curl "$URL&from=$FROM" | tee -a hierarchy.json | jq -r .next_batch); echo $FROM
+
+jq -s 'map(.rooms) | add' hierarchy.json > libregamingspaces.json
+./script.py > space.html
+```
+
 # License
 
 Everything on this repository is licensed as CC0