Update README

Signed-off-by: davidarendsen <davidarendsen@hey.com>

README.md

@@ -1 +1,36 @@
-# fluxquerybuilder
+# InfluxDB 2.x Flux Query Builder
+
+With this query builder you can build queries for Flux.
+See https://docs.influxdata.com/influxdb/v2.3/query-data/flux/
+
+## Installation
+
+```
+composer require arendsen/fluxquerybuilder
+```
+
+## Example usage
+
+```php
+<?php
+
+use Arendsen\FluxQueryBuilder\QueryBuilder;
+use Arendsen\FluxQueryBuilder\Expression\KeyValue;
+
+$queryBuilder = new QueryBuilder();
+$queryBuilder->fromBucket('test_bucket')
+    ->fromMeasurement('test_measurement')
+    ->addRangeStart('-3h')
+    ->addFilter(
+        KeyValue::setEqualTo('_field', 'username')
+            ->orEqualTo('_field', 'email')
+    )
+    ->addMap('r with name: r.user')
+    ->addGroup(['_field', 'ip']);
+```
+
+## Testing
+
+```
+php vendor/bin/phpunit --testdox
+```