A small note about rc.conf and kld_list

[mrcrilly]

I believe this small note could be beneficial. It introduces the reader to the potentially new idea of man pages, and it helps them appreciate that kld_list has a particular format and can actually be used to load multiple kernel modules.

See the #community channel on Discord @ 2030 AEST for an example of a potential failure on our part to explain this correctly (at a time when it could be important.)

[grahamperrin]

I guess, this tip arises partly from cases where people mistakenly create one kld_list line per module to load … true?

Found (thanks):

https://discord.com/channels/727023752348434432/757543661058654269/1106156710650974258

[grahamperrin]

Suggested change

	If you're unfamiliar with the `/etc/rc.conf` file and the `kld_list` option, then checkout the link:https://man.freebsd.org/cgi/man.cgi?rc.conf[`rc.conf`] manpage and search for `kld_list`. Given the importance of this flag, it's important you make yourself familiar with its format in case you need to load multiple kernel modules in the future.
	If you're unfamiliar with the [.filename]#/etc/rc.conf# file and the `kld_list` variable, then see the man:rc.conf[5] manual page and search for _kld_list_.
	If ever you're guided to _add_ or _create_ a `kld_list` line: take care to not create two or more lines. If multiple kernel modules are required, you must list them in a single line (as explained in the manual page).

[bsdimp]

As described in the link:https://man.freebsd.org/cgi/man.cgi?rc.conf[`rc.conf`] manpage, `kld_list` should be specified only once with all the modules to load. Options in the `/etc/rc.conf` file specified multiple times override prior values rather than add to them. Sometimes instructions guide the user to add a `kld_list` option without spelling out that new values should be appended to the old instead of adding multiple lines.

Is my suggestion (though github is rendering it in a way that's ugly, sorry. The original says the word important too many time, and doesn't present at least a gloss of the most important thing: don't have multiple lines specifying the same option. I'm unsure if it should include 'search for it' or not (I opted not in my suggestion).