Add possiblity to share gallerie with public link

.env.example

@@ -41,7 +41,7 @@ OAUTH_ONLY=False
 # Space-separated OAuth2 scopes
 #OAUTH_SCOPE=openid profile email
 
-# Database engine: 'sqlite' or 'postgres'
+# Database engine: 'sqlite', 'postgres' or 'mariadb'
 DB_ENGINE=sqlite
 
 # PostgreSQL settings (only used when DB_ENGINE=postgres)
@@ -51,5 +51,12 @@ DB_ENGINE=sqlite
 #DB_HOST=localhost
 #DB_PORT=5432
 
+# MariaDB settings (only used when DB_ENGINE=mariadb)
+#DB_NAME=photo21
+#DB_USER=photo21
+#DB_PASSWORD=
+#DB_HOST=localhost
+#DB_PORT=3306
+
 # SQLite settings (only used when DB_ENGINE=sqlite)
 #DB_PATH=/app/data/db.sqlite3