Add getting started to docs

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

docs/00-index.md

@@ -2,8 +2,9 @@
 
 Welcome to the documentation of the PHP Flux Query Builder.
 
-* [InfluxDB concepts](01-what-is-influxdb.md)
-* [What is Flux?](02-what-is-flux.md)
+* [Getting started](01-getting-started.md)
+* [InfluxDB concepts](02-what-is-influxdb.md)
+* [What is Flux?](03-what-is-flux.md)
 * [Official InfluxDB documentation](https://docs.influxdata.com/influxdb/v2.6/query-data/flux/)
 
 

docs/01-getting-started.md

@@ -0,0 +1,46 @@
+# Flux Query Builder Docs
+
+## Getting started
+
+Install the package with composer:
+```
+composer require arendsen/fluxquerybuilder
+```
+
+
+```php
+<?php
+
+use Arendsen\FluxQueryBuilder\QueryBuilder;
+use Arendsen\FluxQueryBuilder\Expression\KeyFilter;
+use Arendsen\FluxQueryBuilder\Expression\Map;
+use Arendsen\FluxQueryBuilder\Expression\Selection;
+
+$queryBuilder = new QueryBuilder();
+$queryBuilder->fromBucket('test_bucket')
+    ->addRangeStart(new DateTime('3 hours ago'))
+    ->fromMeasurement('test_measurement')
+    ->addFieldFilter(['username', 'email'])
+    ->addKeyFilter(
+        KeyFilter::setEqualTo('_field', 'username')
+            ->orEqualTo('_field', 'email')
+    )
+    ->limit(50);
+
+echo $queryBuilder->build();
+```
+
+Which will result in the following Flux query:
+
+```js
+from(bucket: "test_bucket") 
+    |> range(start: time(v: 2022-12-28T13:21:11Z)) 
+    |> filter(fn: (r) => r._measurement == "test_measurement") 
+    |> filter(fn: (r) => 
+        r._field == "username" or r._field == "email"
+    ) 
+    |> filter(fn: (r) => 
+        r._field == "username" or r._field == "email"
+    ) 
+    |> limit(n: 50, offset: 0)
+```