cargo-insta --disable-nextest-doctest: Add -N short option

I'm not sure how appropriate this is for general use, but it's
convenient if, like me, you have a project where you use this all the
time.

cargo-insta/src/cli.rs

@@ -171,7 +171,7 @@ struct TestRunnerOptions {
     #[arg(long)]
     target: Option<String>,
     /// Do not run `cargo test --doc` after `cargo nextest`, even if test specifiers would otherwise include doctests.
-    #[arg(long)]
+    #[arg(long, short = 'N')]
     disable_nextest_doctest: bool,
 }
 
@@ -882,7 +882,7 @@ fn prepare_test_runner<'snapshot_ref>(
         None
     };
     let mut prevents_doc_run = false;
-    if cmd.disable_nextest_doctest {
+    if cmd.test_runner_options.disable_nextest_doctest {
         prevents_doc_run = true;
     }
     if cmd.target_args.all || cmd.target_args.workspace {