Add comment about NoDelay=true in systemd docs

[evenreven]

Description

Since NoDelay apparently is no longer the default, the example in the systemd docs should also reflect this. This follows up #2631.

If the line should be removed instead of commented out (or if the added comment is unclear or unhelpful), please let me know!

(This is my first PR here, and I hope I've ticked the right boxes. Sorry if I overlooked anything!)

Your checklist for this pull request

• I have reviewed the guidelines for contributing to this repository.
• I have added (or updated) appropriate tests if this PR fixes a bug or adds a feature.
• My pull request is 100 lines added/removed or less so that it can be easily reviewed.
• If this PR doesn't need tests (docs change), I added [ci skip] to the title of the PR.
• If this closes any issues, I have added "Closes #issue" to the PR description or my commit messages.
• I have updated the documentation accordingly.
• All new and existing tests passed, including Rubocop.

[dentarg]

Another option could be to just remove this line and trust that people using the low_latency option and systemd, understands that they should also use the NoDelay option in systemd, as the Puma docs do mention TCP_NODELAY:

puma/lib/puma/dsl.rb

Lines 256 to 258 in 32e011a

	# * Set whether to optimize for low latency instead of throughput with
	# +low_latency+, default is to not optimize for low latency. This is done
	# via +Socket::TCP_NODELAY+.

[nateberkopec]

Poke @evenreven

[evenreven]

Sorry for the delay, @dentarg and @nateberkopec! I committed @dentarg's suggestion now, but I'd be open to just remove the lines altogether if you prefer that. That's your call.