Add documentation for autocompressor (#70)

docs/python.md

@@ -0,0 +1,54 @@
+# Running the compressor tools from python
+
+Both the automatic and manual tools use PyO3 to allow the compressor
+to be run from Python. 
+
+To see any output from the tools, logging must be setup in Python before
+the compressor is run.
+
+## Setting things up
+
+1. Create a virtual environment in the place you want to use the compressor from
+(if it doesn't already exist)  
+`$ virtualenv -p python3 venv`
+
+2. Activate the virtual environment and install `maturin` (if you haven't already)  
+`$ source venv/bin/activate`  
+`$ pip install maturin`  
+
+3. Navigate to the correct location  
+For the automatic tool:  
+`$ cd /home/synapse/rust-synapse-compress-state/auto_compressor`   
+For the manual tool:  
+`$ cd /home/synapse/rust-synapse-compress-state`   
+
+3. Build and install the library  
+`$ maturin develop`
+
+This will install the relevant compressor tool into the activated virtual environment.
+
+## Automatic tool example:
+
+```python
+import auto_compressor
+
+auto_compressor.compress_state_events_table(
+  db_url="postgresql://localhost/synapse",
+  chunk_size=500,
+  default_levels="100,50,25",
+  number_of_chunks=100
+)
+```
+
+# Manual tool example:
+
+```python
+import synapse_compress_state
+
+synapse_compress_state.run_compression(
+  db_url="postgresql://localhost/synapse",
+  room_id="!some_room:example.com",
+  output_file="out.sql",
+  transactions=True
+)
+```