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/neon.go

@@ -32,8 +32,9 @@ import (
 
 func neonRegistration() *Registration {
 	return &Registration{
-		Provider:    coredata.ConnectorProviderNeon,
-		DisplayName: "Neon",
+		Provider:         coredata.ConnectorProviderNeon,
+		DisplayName:      "Neon",
+		DocumentationURL: accessReviewDocsURL("neon"),
 		// Neon's API authenticates with an API key (napi_...) presented
 		// as Authorization: Bearer, the default APIKeyConnection scheme.
 		// Neon's OAuth is partner-gated (manual application), so the