Enable multiple co-chair members

[manuelfuenmayor]

From /~https://github.com/metanorma/mn-samples-ieee-private/pull/9

In the meantime, I have encoded it like:

:wg-chair: Mark Kaufman; Timothy Wilmering

[manuelfuenmayor]

Also, I don't know which doctype correspond to the boilerplace shown above:
"At the time this standard was submitted to the IEEE-SA Standards Board for approval, the Diagnostics and
Maintenance Control subcommittee had the following membership:"

The one that I get is:
"At the time this draft Standard was completed, the Diagnostics and Maintenance Control Working Group had the following membership:"
(Setting the attribute :working-group: Diagnostics and Maintenance Control)

[ronaldtse]

@manuelfuenmayor for the "At the time..." phrase, can you compare the three IEEE master documents to see if we can settle the correct format? Thanks.

[manuelfuenmayor]

I have opened another ticket to discuss the "boilerplate" subject.

[opoudjis]

Obsolete: you can implement this now as:

item::
name::: Mark Kaufman
role::: Co-chair
item::
name::: Timothy Wilmering
role::: Co-chair

[opoudjis]

"At the time this draft Standard was completed, the Diagnostics and Maintenance Control Working Group had the following membership:"

We are allowing all the text to be user-supplied other than the initial sentence of each participants subsection. @manuelfuenmayor @ronaldtse If we must make that be user-supplied as well, we will, but I'd really rather avoid that.

[opoudjis]

Closing this ticket in favour of #105 ; the co-chair issue has been resolved.