Refactor terminology and improve clarity across templates

- Updated "Termin" to "Buchung" in admin_dashboard.html and appointments.html for consistency.
- Enhanced language for better understanding in various templates, including base.html, dienstleistungen.html, inventarsystem.html, kontakt.html, login.html, main.html, projekte.html, register.html, team.html, and added a new tutorial.html.
- Corrected spelling and grammatical errors throughout the templates.
- Improved user guidance and descriptions for better user experience.

Website/templates/login.html

@@ -93,7 +93,7 @@
 {% block content %}
 <section class="auth-wrap">
   <h1>Login</h1>
-  <p>Bitte melden Sie sich mit Ihrem Konto an, um Termine anzufragen.</p>
+  <p>Bitte melden Sie sich mit Ihrem Konto an, um Buchungen anzufragen.</p>
   <form method="POST" action="{{ url_for('login') }}">
     <div class="field">
       <label for="username">Benutzername</label>