docs: add PHP getting started guide (#442)

Co-authored-by: Clément Vannicatte <[email protected]>

Author: damcou

website/docs/api-clients/installation.mdx

@@ -9,7 +9,8 @@ import TabItem from '@theme/TabItem';
   groupId="language"
   defaultValue="js"
   values={[
-    { label: 'JavaScript', value: 'js', }
+    { label: 'JavaScript', value: 'js', },
+    { label: 'PHP', value: 'php', }
   ]
 }>
 <TabItem value="js">
@@ -111,5 +112,41 @@ const res = await personalizationClient.getUserTokenProfile({
 console.log('[Results]', res);
 ```
 
+</TabItem>
+
+<TabItem value="php">
+
+## Installation
+
+First, install Algolia PHP API Client via the composer package manager:
+```bash
+composer require algolia/algoliasearch-client-php
+```
+## Using the client
+
+Then, create objects on your index:
+```php
+$client = Algolia\AlgoliaSearch\Api\SearchClient::create(
+    '<YOUR_APP_ID>',
+    '<YOUR_API_KEY>'
+);
+
+$client->saveObject('<YOUR_INDEX>', ['objectID' => 1, 'name' => 'Foo']);
+```
+
+Finally, you may begin searching an object using the `search` method:
+```php
+$objects = $client->search('<YOUR_INDEX>', ['query' => 'Foo']);
+```
+
+Another example with the personalization client:
+```php
+$client = Algolia\AlgoliaSearch\Api\PersonalizationClient::create(
+    '<YOUR_APP_ID>',
+    '<YOUR_API_KEY>'
+);
+
+$res = $client->getUserTokenProfile('<YOUR_TOKEN>');
+```
 </TabItem>
 </Tabs>