github.go: adjust organization not found error message to indicate that org was manually specified in configuration (#45918)

CHANGELOG.md

@@ -27,6 +27,7 @@ All notable changes to Sourcegraph are documented in this file.
 ### Changed
 
 - Code Insights no longer uses a custom index of commits to compress historical backfill and instead queries the repository log directly. This allows the compression algorithm to span any arbitrary time frame, and should improve the reliability of the compression in general. [#45644](https://github.com/sourcegraph/sourcegraph/pull/45644)
+- GitHub code host configuration: The error message for non-existent organizations has been clarified to indicate that the organization is one that the user manually specified in their code host configuration. [#45918](https://github.com/sourcegraph/sourcegraph/pull/45918)
 - Git blame view got a user-interface overhaul and now shows data in a more structured way with additional visual hints. [#44397](https://github.com/sourcegraph/sourcegraph/issues/44397)
 
 ### Fixed

internal/repos/github.go

@@ -440,7 +440,7 @@ func (s *GitHubSource) listOrg(ctx context.Context, org string, results chan *gi
 				if page == 1 {
 					var e *github.APIError
 					if errors.As(err, &e) && e.Code == 404 {
-						oerr = errors.Errorf("organisation %q not found", org)
+						oerr = errors.Errorf("organisation %q (specified in configuration) not found", org)
 						err = nil
 					}
 				}