docs(storage): update broken links for SignURL and PostPolicy (#6779)

storage/bucket.go

@@ -170,7 +170,7 @@ func (b *BucketHandle) Update(ctx context.Context, uattrs BucketAttrsToUpdate) (
 // for this method.
 //
 // [Overview of access control]: https://cloud.google.com/storage/docs/accesscontrol#signed_urls_query_string_authentication
-// [automatic detection of credentials]: https://pkg.go.dev/cloud.google.com/go/storage#hdr-Credential_requirements_for_[BucketHandle.SignedURL]_and_[BucketHandle.GenerateSignedPostPolicyV4]
+// [automatic detection of credentials]: https://pkg.go.dev/cloud.google.com/go/storage#hdr-Credential_requirements_for_signing
 func (b *BucketHandle) SignedURL(object string, opts *SignedURLOptions) (string, error) {
 	if opts.GoogleAccessID != "" && (opts.SignBytes != nil || len(opts.PrivateKey) > 0) {
 		return SignedURL(b.name, object, opts)
@@ -212,7 +212,7 @@ func (b *BucketHandle) SignedURL(object string, opts *SignedURLOptions) (string,
 // to be non-nil. You may need to set the GoogleAccessID and PrivateKey fields
 // in some cases. Read more on the [automatic detection of credentials] for this method.
 //
-// [automatic detection of credentials]: https://pkg.go.dev/cloud.google.com/go/storage#hdr-Credential_requirements_for_[BucketHandle.SignedURL]_and_[BucketHandle.GenerateSignedPostPolicyV4]
+// [automatic detection of credentials]: https://pkg.go.dev/cloud.google.com/go/storage#hdr-Credential_requirements_for_signing
 func (b *BucketHandle) GenerateSignedPostPolicyV4(object string, opts *PostPolicyV4Options) (*PostPolicyV4, error) {
 	if opts.GoogleAccessID != "" && (opts.SignRawBytes != nil || opts.SignBytes != nil || len(opts.PrivateKey) > 0) {
 		return GenerateSignedPostPolicyV4(b.name, object, opts)