Merge pull request #687 from felix920506/tmdb-china-warning

Add warning for metadata providers in mainland china

docs/general/server/metadata/index.md

@@ -14,3 +14,16 @@ Jellyfin can get metadata for your media through multiple sources. By default, J
 [^1]: OMDb only provides English metadata.
 
 There are more official providers available in our [Plugin Catalog](/docs/general/server/plugins#official-plugins), like TheTVDB, fanart.tv or AniDB. If you still can't find the provider you are looking for, you could even develop your own with our Plugin API.
+
+:::caution Notice for Users in Mainland China 中国大陆地区用户请注意
+
+Because of external factors, certain metadata providers may not be accessable in mainland China. <br />
+由于外部因素，部分元数据提供者在中国大陆地区可能无法访问。
+
+Below is a list of known inaccessable providers: <br />
+下方为已知无法访问的提供者：
+
+- The Movie Database (TMDb)
+- TheTVDB
+
+:::