Tidy up command descriptions

Rewordings and removal of superfluous newlines.

Signed-off-by: Hidde Beydals <hello@hidde.co>

cmd/flux/create_alertprovider.go

@@ -49,8 +49,7 @@ var createAlertProviderCmd = &cobra.Command{
   flux create alert-provider github-podinfo \
   --type github \
   --address https://github.com/stefanprodan/podinfo \
-  --secret-ref github-token
-`,
+  --secret-ref github-token`,
 	RunE: createAlertProviderCmdRun,
 }