Fix/update usage docs

docs/usage.md

@@ -2,17 +2,26 @@
 
 You can use the `clean-scraper` command-line tool to scrape available agencies by supplying agency slugs. It will write files, by default, to a hidden directory in the user's home directory. On Apple and Linux systems, this will be `~/.clean-scraper`.
 
+To run a scraper, you must first know its agency "slug" (a state postal code + short agency name):
+
+You can list available agencies (and get their slugs) using the `list` subcommand:
+
 ```bash
-# Scrape a single state
-clean-scraper ca_san_diego_pd
+clean-scraper list
+```
+
+You can then run a scraper for an agency using its slug:
+
+```bash
+clean-scraper scrape ca_san_diego_pd
 ```
 
 To use the `clean` library in Python, import an agency's scraper and run it directly.
 
 ```python
-from clean.ca import import san_diego_pd as sdpd
+from clean.ca import san_diego_pd
 
-sdpd.scrape()
+san_diego_pd.scrape()
 ```
 
 ## Configuration
@@ -22,19 +31,14 @@ You can set the `CLEAN_OUTPUT_DIR` environment variable to specify a different d
 Use the `--help` flag to view additional configuration and usage options:
 
 ```bash
-clean-scraper --help
-
-Usage: python -m warn [OPTIONS] [STATES]...
+Usage: clean-scraper [OPTIONS] COMMAND [ARGS]...
 
-  Command-line interface for downloading law enforcement agency files.
-
-  SLUGS -- a list of one or agency slugs to scrape.
+  Command-line interface for downloading CLEAN files.
 
 Options:
-  --data-dir PATH                 The Path were the results will be saved
-  --cache-dir PATH                The Path where results can be cached
-  --delete / --no-delete          Delete generated files from the cache
-  -l, --log-level [DEBUG|INFO|WARNING|ERROR|CRITICAL]
-                                  Set the logging level
-  --help                          Show this message and exit.
+  --help  Show this message and exit.
+
+Commands:
+  list    List all available agencies and their slugs.
+  scrape  Command-line interface for downloading CLEAN files.
 ```