Documentation: obs_common_subset typos, corrections

What's the issue?

📚 obs_common_subset.html has several minor mistakes I'd like to note as I'm reading.

Where did you find the issue?

assimilation_code/programs/obs_common_subset/obs_common_subset.html
https://docs.dart.ucar.edu/en/latest/assimilation_code/programs/obs_common_subset/obs_common_subset.html#program-obs-common-subset

What needs to be fixed?

"obs_selection_tool" is named "obs_selection", and the text is not a link.

"list of lists of filenames" would be clearer as "list of files, each containing a list of obs_seq files"

ls exp3/*/obs_seq.final > exp3list
cat exp2list

filename_seq_list = 'exp1list', 'exp2list', exp3list' Needs a ' before exp3list

In the table of namelist entries we might want to change "printed every Nth set of obs"
to "printed at multiples of print_every"

Building: "Most $DART/models/*/work directories" would more accurately (but less robustly) be
"Most $DART/models/*/work/quick_build.sh"

Anything else we should know?

Open assimilation_code/programs/obs_common_subset/obs_common_subset.html and review the listed wording, link, command, quoting, table, and build-path corrections. Done when each requested correction is applied and the linked obs_common_subset documentation page shows the revised text.