docs: improvements to the readme (#52)

Co-authored-by: Marie Gauthier <[email protected]>

README.md

@@ -1,10 +1,85 @@
 # indexer
 
-Blockchain indexer and database
+This project indexes data from the [Regen Ledger](https://github.com/regen-network/regen-ledger/) and stores it in a postgresql database.
+It is built as single python script that spawns independent processes for indexing application specific data.
+This database is currently being used for several purposes in relation to [the Regen Marketplace](https://github.com/regen-network/regen-web) and [the Regen Groups UI](https://github.com/regen-network/groups-ui).
+
+## GraphQL API
+
+The [Regen Server](https://github.com/regen-network/regen-server/) provides a GraphQL API for accessing the indexer database:
+
+https://api.regen.network/indexer/v1/graphiql
+
+Both the Regen Groups UI and the Regen Marketplace use this API to access the data.
+
+## Dependencies
+
+In order to run this project locally you will need the following:
+
+1. a [local testnet](https://docs.regen.network/ledger/get-started/local-testnet.html) version of regen-ledger with REST API and RPC enabled
+2. a postgresql database running, either locally or through [docker](#local-development-with-docker)
+3. a working python3 installation
+4. the [poetry package manager](https://python-poetry.org/docs/#installation) for python installed
+
+## Configuration
+
+All configuration values are set up via environment variables, see `.env-example`.
+During local development these values will be something like:
+
+```
+DATABASE_URL=postgres://postgres:postgres@localhost:5432/indexer
+REGEN_RPC=http://localhost:26657
+REGEN_API=http://localhost:1317
+```
+
+The `DATABASE_URL` is used both for the application to connect as well as the migration tool.
+
+## Architecture
+
+The main entrypoint script is `main.py`, this script spawns all other indexing processes.
+The primary indexing process is contained in `index_blocks.py`, this process indexes all block-level data by looping through transactions and messages.
+
+The scripts that index regen-specific application data are:
+
+- `index_class_issuers.py`
+- `index_proposals.py`
+- `index_retires.py`
+- `index_votes.py`
+
+## Running the main script
+
+After successfully running a local testnet version of Regen Ledger and preparing a database you can run the scripts with:
+
+```
+$ poetry install
+$ poetry run python main.py
+```
+
+## Managing the database with migrations
+
+See [migrations/README.md](migrations/README.md).
+
+## Heroku Deployment
+
+This application is deployed in a pipeline in heroku.
+There is a staging environment in addition to the production environment.
+
+## Local development with docker
+
+You can make use of docker to bring up the various components required for development.
+See the `docker-compose.yml` for information on what the components are.
+The following command will bring up the system:
+
+```
+docker-compose up
+```
 
 ## E2E Testing
 
-This project uses docker for e2e testing.
+Currently we have a set of e2e tests written using the Regen CLI and shell scripts.
+This project uses docker for e2e testing in CI.
+
+### Instructions for running e2e tests with docker
 
 Build docker containers (this only needs to be run once or after making changes):