Changed update to install

.github/CONTRIBUTING.md

@@ -4,7 +4,7 @@ Contributing
 Before you contribute code to php-telegram-bot, please make sure it conforms to the PSR-2 coding standard and that the php-telegram-bot unit tests still pass. The easiest way to contribute is to work on a checkout of the repository, or your own fork. If you do this, you can run the following commands to check if everything is ready to submit:
 
     cd php-telegram-bot
-    composer update
+    composer install
     ./vendor/bin/phpcs --standard=phpcs.xml -sp --encoding=utf-8 src/ --report-width=150
 
 Which should give you no output, indicating that there are no coding standard errors. And then: