add `sample-litd.conf`

[ZZiigguurraatt]

There is no sample-litd.conf in this repository. Other projects like lnd and taproot-assets have sample-lnd.conf and sample-tapd.conf respectively.

We can run litd -h to get some options, but the sample files are often nice to review before you even download and install the litd binary so you can see what the options are that you could set. Also, I'm not sure where someone even finds out about the litd -h command line option.

Running litd -h does give a bunch of stuff that is carryover from all the subservers, but I think sample-litd.conf should only include the options that are litd specific and then reference sample-lnd.conf, sample-tapd.conf, etc. for the rest of the samples.

[victorabarros]

I hope this is helpful! 🤗
#1325