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.

.gitignore

@@ -4,4 +4,5 @@ Inventarsystem_Lizenz_Verwaltung
 main.dist
 .mongo-data
 db
-build
+build
+mongodb.log