quote command part option undocumented

[jrandall]

In the spec, a command part option named quote is listed: https://github.com/broadinstitute/wdl/blob/develop/SPEC.md#command-part-options

However, although the spec goes on to have a subsection explaining the other four options (sep, true, false, and default) there appears to be no documentation of what is meant by the quote option.