fix(docs): Configure SWA to never emit trailing slashes for website U…

…RLs (microsoft#23286)

Ensures consistent relative file path link behavior by ensuring resolved
site URLs never include a trailing slash. See
<https://learn.microsoft.com/en-us/azure/static-web-apps/configuration#never>

Also makes some small fixes to config files for local development.


[AB#25895](https://dev.azure.com/fluidframework/235294da-091d-4c29-84fc-cdfc3d90890b/_workitems/edit/25895)

docs/static/staticwebapp.config.json

@@ -14,5 +14,6 @@
 			"route": "/404",
 			"statusCode": 404
 		}
-	]
+	],
+	"trailingSlash": "never"
 }