The file format for each option now features a "Example:" header that
can provide one or more examples that get rendered appropriately in the
output. All options MUST have at least one example or gen.pl complains
at build-time.
This fix also does a few other minor format and consistency cleanups.
Closes#7654
Under condition using http_proxy env var, noproxy list was the
combination of --noproxy option and NO_PROXY env var previously. Since
this commit, --noproxy option overrides NO_PROXY environment variable
even if use http_proxy env var.
Closes#1140