docs(bandcamp): add note about slow loading for large labels (#76)

Based on music-assistant/server#3069
Add a user-friendly explanation of the Bandcamp rate-limiting issue that
causes slow loading times when browsing labels with large catalogs.
Documents the retry behavior users will see in logs and clarifies that
this is an external limitation that cannot be bypassed.

Author: OzGav

docs/music-providers/bandcamp.md

@@ -51,5 +51,8 @@ Music Assistant has support for Bandcamp. Contributed and maintained by [ALERTua
 ## Known Issues / Notes
 
 - This provider mimics Bandcamp. Do not expect to see the same search results as you would when using Bandcamp itself
-- Some low quality artwork can be expected when using this provider
-- Tracks lack album art
+- **Slow Loading for Large Labels**: When browsing a music label with a large catalog (dozens to hundreds of albums),
+  indexing may take several minutes. This happens because Bandcamp limits how quickly data can be retrieved from
+  their servers. You'll see multiple retry attempts in the logs with messages like "Bandcamp rate limit reached"
+  followed by delays between each attempt. This is a limitation imposed by Bandcamp's service and cannot be
+  bypassed — the system must wait between requests to avoid being blocked entirely.