message: README: Add NPM package information
diff: @@ -13,20 +13,35 @@ used to maintain the following changelogs:
  - [indexer-service](packages/indexer-service/CHANGELOG.md)
  - [indexer-agent](packages/indexer-agent/CHANGELOG.md)
  -## Install dependencies
  +## Running from NPM packages
  -Run the following at the root of this repository:
  +The indexer service and agent can be installed as NPM packages, using
  ```sh
  -yarn
  +npm install -g @graphprotocol/indexer-service --registry https://testnet.thegraph.com/npm-registry/
  +npm install -g @graphprotocol/indexer-agent --registry https://testnet.thegraph.com/npm-registry/
  ```
  -## Build
  +After that, they can be
  +
  +## Running from source
  +
  +Run the following at the root of this repository to install dependencies and build the packages:
  +
  +```sh
  +yarn
  +```
  -The following command builds all packages in this repository:
  +After this, the indexer service and agent can be run with:
  ```sh
  -yarn prepare
  +# Indexer service
  +cd packages/indexer-service
  +./bin/graph-indexer-service ...
  +
  +# Indexer agent
  +cd packages/indexer-service
  +./bin/graph-indexer-service ...
  ```
  ## Docker images
  