Add GitHub default account

Author: pH-7

src/Command/Markdown/GeneratorCommand.php

@@ -234,7 +234,7 @@ private function isValidUrl(string $url): bool
 
     private function promptGithub(SymfonyStyle $io): string
     {
-        $github = $io->ask('GitHub Username (github.com/<username>)');
+        $github = $io->ask('GitHub Username (github.com/<username>)', DefaultValue::GITHUB);
 
         if (!$this->isFieldFilled($github)) {
             throw new EmptyFieldException('GitHub nickname is required.');

src/DefaultValue.php

@@ -12,6 +12,7 @@ final class DefaultValue
 {
     public const AUTHOR = 'Pierre-Henry Soria';
     public const EMAIL = 'hi@ph7.me';
+    public const GITHUB = 'pH-7';
     public const LICENSE_CODE = License::MIT_CODE;
     public const DESTINATION_FILE = ROOT_DIR . '/tmp';
     public const GRAVATAR_SIZE = 200;