Update link in yaml-providers.md (apache#34570)

Replace Polber link with [beam-starter-java-provider] link (https://github.com/apache/beam-starter-java-provider)

Author: shubham-j-sde

website/www/site/content/en/documentation/sdks/yaml-providers.md

@@ -41,7 +41,7 @@ four main steps:
    which provides an identifier used to refer to this transform later as well
    as metadata like a human-readable description and its configuration parameters.
 3. Building a Jar that contains these classes and vends them via the
-   [Service Loader](https://github.com/Polber/beam-yaml-xlang/blob/95abf0864e313232a89f3c9e57b950d0fb478979/src/main/java/org/example/ToUpperCaseTransformProvider.java#L30)
+   [Service Loader](https://github.com/apache/beam-starter-java-provider/blob/main/src/main/java/org/example/ToUpperCaseTransformProvider.java#L47)
    infrastructure.
 4. Writing a [provider specification](https://beam.apache.org/documentation/sdks/yaml/#providers)
    that tells Beam YAML where to find this jar and what it contains.