Update MultiTenancy documentation with instructions how to configure separate qgs-resources directories

Author: manisandro

src/topics/MultiTenancy.md

@@ -104,6 +104,7 @@ A minimal configuration for tenant `tenant_name` may look as follows:
     "tenant": "tenant_name",
     "default_qgis_server_url": "http://qwc-qgis-server/ows/",
     "config_db_url": "postgresql:///?service=qwc_configdb",
+    "qgis_projects_base_dir": "/data",
     "qgis_projects_scan_base_dir": "/data/tenant_name/scan"
     ...
   },
@@ -151,6 +152,11 @@ A minimal configuration for tenant `tenant_name` may look as follows:
 * The `qwc2_config_file`, `qwc2_index_file`, `qwc2_base_dir` and `qwc2_path` paths will determine whether the viewer build/configuration is shared or separate for each tenant.
 * To use a separate assets folder for each tenant, you can set an appropriate `assetsPath` in the `qwc2_config_file` of each tenant.
 * The various service URLs in the `mapViewer` configuration and in other service configurations need to match what is expected in the `api-gateway` configuration.
+* To separate the qgis projects per tenant (avoiding the `<tenantname>/` prefix on the map names), you can proceed as follows:
+  - Create subdirectories for each tenant in `volumes/qgs-resources`, i.e. `volumes/qgs-resources/<tenant_name>`,
+  - Set `default_qgis_server_url` to `http://qwc-qgis-server/ows/<tenant_name>`,
+  - Set `qgis_projects_base_dir` to `/data/<tenant_name>`,
+  - Make sure to remove the `/ows` prefix from the `url` of any manually configured themes in `themesConfig.json`.
 
 ## `tenantConfig` template