Link the 19 API-key access-review connector docs

Each of these providers ships an API-key connection path and a driver, but
no Registration carried a DocumentationURL, so the console rendered no
"how do I get this token" link on the connect dialog. probo.com now has a
page per provider, so point each Registration at it.

Slugs are passed explicitly rather than derived from the enum, per
accessReviewDocsURL's contract, so BETTER_STACK maps to better-stack and
INCIDENT_IO to incident-io.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/connector/provider/metabase.go

@@ -34,11 +34,12 @@ import (
 
 func metabaseRegistration() *Registration {
 	return &Registration{
-		Provider:       coredata.ConnectorProviderMetabase,
-		DisplayName:    "Metabase",
-		SupportsAPIKey: true,
-		APIKeyHeader:   "x-api-key",
-		BuildProbeURL:  buildMetabaseProbeURL,
+		Provider:         coredata.ConnectorProviderMetabase,
+		DisplayName:      "Metabase",
+		DocumentationURL: accessReviewDocsURL("metabase"),
+		SupportsAPIKey:   true,
+		APIKeyHeader:     "x-api-key",
+		BuildProbeURL:    buildMetabaseProbeURL,
 		APIKeyExtraSettings: []ExtraSetting{
 			{Key: "instanceUrl", Label: "Instance URL", Required: true},
 		},