Fix README.md param issue
* Update README.md
Fixing README docs missing param in the Running a Local Graph Node section.
* Update README.md
Fixing according to this review:
@@ -43,7 +43,7 @@ Once you have all the dependencies set up, you can run the following:
```
cargo run -p graph-node --release -- \
--postgres-url postgresql://USERNAME[:PASSWORD]@localhost:5432/graph-node \
- --ethereum-rpc [URL] \
+ --ethereum-rpc NETWORK_NAME:[CAPABILITIES]:URL \
--ipfs 127.0.0.1:5001
```
