chore: improve readme
Add admin calls to set writer ID and create a database.
@@ -176,6 +176,31 @@ The server will, by default, start an HTTP API server on port `8080` and a gRPC
### Writing and Reading Data
+Each IOx instance requires a writer ID.
+This can be set three ways:
+- set an environment variable `INFLUXDB_IOX_ID=42`
+- set a flag `--writer-id 42`
+- send an HTTP PUT request:
+```
+curl --request PUT \
+ --url http://localhost:8080/iox/api/v1/id \
+ --header 'Content-Type: application/json' \
+ --data '{
+ "id": 42
+ }'
+```
+
+To write data, you need a destination database.
+This is set via HTTP PUT, identifying the database by org `company` and bucket `sensors`:
+```
+curl --request PUT \
+ --url http://localhost:8080/iox/api/v1/databases/company_sensors \
+ --header 'Content-Type: application/json' \
+ --data '{
+ "store_locally": true
+}'
+```
+
Data can be stored in InfluxDB IOx by sending it in [line protocol] format to the `/api/v2/write`
endpoint. Data is stored by organization and bucket names. Here's an example using [`curl`] with
the organization name `company` and the bucket name `sensors` that will send the data in the
