Small fixes in README

README.md

@@ -4,6 +4,12 @@ First attempt of a PHP client for the [GBIF API](https://www.gbif.org/developer/
 
 A [Drupal module](https://www.drupal.org/project/gbif2) uses this client to enable users to list GBIF occurrences with the Views module on their websites.
 
+## Installation
+
+```
+composer require restelae/php-gbif
+```
+
 ## Usage
 
 ### Get an occurrence knowing its ID (key)