Merge pull request #10333 from iamazeem/9759-gh-extension-install

[gh extensions install] Improve help text and error message

pkg/cmd/extension/command.go

@@ -298,9 +298,18 @@ func NewCmdExtension(f *cmdutil.Factory) *cobra.Command {
 				Long: heredoc.Docf(`
 					Install a GitHub CLI extension from a GitHub or local repository.
 
-					For GitHub repositories, the repository argument can be specified in %[1]sOWNER/REPO%[1]s format or as a full repository URL.
+					For GitHub repositories, the repository argument can be specified in
+					%[1]sOWNER/REPO%[1]s format or as a full repository URL.
 					The URL format is useful when the repository is not hosted on github.com.
 
+					For remote repositories, the GitHub CLI first looks for the release artifacts assuming
+					that it's a binary extension i.e. prebuilt binaries provided as part of the release.
+					In the absence of a release, the repository itself is cloned assuming that it's a
+					script extension i.e. prebuilt executable or script exists on its root.
+
+					The %[1]s--pin%[1]s flag may be used to specify a tag or commit for binary and script
+					extensions respectively, the latest version is used otherwise.
+
 					For local repositories, often used while developing extensions, use %[1]s.%[1]s as the
 					value of the repository argument. Note the following:
 

pkg/cmd/extension/manager.go

@@ -268,7 +268,7 @@ func (m *Manager) Install(repo ghrepo.Interface, target string) error {
 		return err
 	}
 	if !hs {
-		return errors.New("extension is not installable: missing executable")
+		return fmt.Errorf("extension is not installable: no usable release artifact or script found in %s", repo)
 	}
 
 	return m.installGit(repo, target)