doc: use single quotes in --tls-cipher-list

Currently, running the example code will produce the following error in
bash:
$ node --tls-cipher-list="ECDHE-RSA-AES128-GCM-SHA256:!RC4" server.js
bash: !RC4: event not found

This commit changes the two examples to use single quotes to avoid the
shell from trying to interpret '!' as the history command.

PR-URL: https://github.com/nodejs/node/pull/33709


Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>