Update GitHub issue and contributing templates.

[skip ci]

.github/CONTRIBUTING.md

 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:
+The easiest way to contribute is to work on a checkout of your own fork.
+When working on the `core` repository, it makes sense to rename your fork to `php-telegram-bot`.
+
+Before you contribute code, please make sure it conforms to the PSR-2 coding standard and that the unit tests still pass.
+You can run the following commands to check if everything is ready to submit:
 
     cd php-telegram-bot
     composer install
-    ./vendor/bin/phpcs --standard=phpcs.xml -sp --encoding=utf-8 src/ --report-width=150
+    composer check-code
 
-Which should give you no output, indicating that there are no coding standard errors. And then:
+Which should give you no output, indicating that there are no coding standard errors.
+And then (remember to set up your test database!):
 
-    ./vendor/bin/phpunit
+    composer test
 
 Which should give you no failures or errors. You can ignore any skipped tests as these are for external tools.
 
 Pushing
 -------
 
-Development is based on the git flow branching model (see http://nvie.com/posts/a-successful-git-branching-model/ )
+Development is based on the git flow branching model (see http://nvie.com/posts/a-successful-git-branching-model/)
 If you fix a bug please push in hotfix branch.
 If you develop a new feature please create a new branch.
 
@@ -30,8 +35,8 @@ Further code convention adopted
 
 - Each method and class is documented with a docblock
 
-Example for a function or methods:
-```
+Example for a function or method:
+```php
 /**
  * Get formatted date
  *
@@ -42,7 +47,7 @@ Example for a function or methods:
 ```
 
 - Each file is provided with the following header:
-```
+```php
 /**
  * This file is part of the TelegramBot package.
  *

.github/ISSUE_TEMPLATE.md

 ### Required Information
-
+<!-- Please enter exact version numbers! -->
+- Operating system:
 - PHP version:
 - PHP Telegram Bot version:
 - Using MySQL database: yes / no
+- MySQL version:
 - Update Method: Webhook / getUpdates
 - Self-signed certificate: yes / no
 - RAW update (if available):