README: add usage instructions

README.md

@@ -2,6 +2,21 @@
 
 Clone of https://botsin.space/@PosiBot for freaks. Currently deployed at https://freak.university/@FreakPos.
 
+## Usage
+
+```
+pip install -r requirements.txt
+cp config.example.toml config.toml
+```
+
+Then, edit config.toml with your access token and instance. 
+Now edit your crontab (`crontab -e`) and add a line to periodically run freakpos.py.
+For example, this posts every four hours with a random delay:
+
+```
+15 */4 * * * bash -c 'sleep $(( $RANDOM \% (60 * 60 * 4) )) && path/to/FreakPositivity/freakpos.py'
+```
+
 ## License
 
 AGPL-3.0-or-later, see LICENSE