README for esd crawler

crawlers/esd/README.md

@@ -3,3 +3,28 @@
 This crawler retrieves Ethereum function signatures from the Ethereum Signature Database at
 [https://4byte.directory](https://4byte.directory).
 
+### Installation
+
+(Use Python 3)
+
+```bash
+pip install -r requirements.txt
+```
+
+### Database access
+
+Make sure that the `EXPLORATION_DB_URI` environment variable is set as a Postgres connection string.
+
+For a sample, view [`sample.env`](./sample.env).
+
+### Crawling ESD function signatures
+
+```bash
+python esd.py --interval 0.3 functions
+```
+
+### Crawling ESD event signatures
+
+```bash
+python esd.py --interval 0.3 events
+```