comm-ref processing

[Intelligent2013]

Source: https://github.com/metanorma/mn-samples-bsi/issues/2
Related issue: metanorma/mn2sts#47

Source STS XML possible values in samples:

<comm-ref>TDW/4</comm-ref>
<comm-ref>ISO/IEC JTC 1/SC 27</comm-ref>
<comm-ref>IST/33/5</comm-ref>
<comm-ref>TDW/4/7</comm-ref>
<comm-ref>MS/2/-/3</comm-ref>
<comm-ref>B/555</comm-ref>
<comm-ref>CW/29</comm-ref>
<comm-ref>ISO/TC 37/SC 3</comm-ref>
<comm-ref>TS/1</comm-ref>
<comm-ref>SPSC</comm-ref>
<comm-ref>SVS/1/4</comm-ref>
<comm-ref>ISO/TC 286</comm-ref>
<comm-ref>B/517/1</comm-ref>
<comm-ref>GW/3</comm-ref>
<comm-ref>HCS/1/2</comm-ref>
<comm-ref>CEN/TC 389</comm-ref>
<comm-ref>IMS/1</comm-ref>
<comm-ref>FSH/12/4</comm-ref>
<comm-ref>DEF/1</comm-ref>
<comm-ref>ISO/PC 286</comm-ref>

Current version of sts2mn converts non-parsed (i.e. without components TC, SC and WG) values into MN XML:

<editorialgroup>
<technical-committee number="DEF/1"/>
<secretariat/>
</editorialgroup>

But metanorma process adoc data :bsi-related: Committee reference DEF/1; Draft for comment 20/30387670 DC into

<relation type="related">
<bibitem>
<title>--</title>
<docidentifier>Committee reference DEF/1</docidentifier>
</bibitem>
</relation>
<relation type="related">
<bibitem>
<title>--</title>
<docidentifier>Draft for comment 20/30387670 DC</docidentifier>
</bibitem>
</relation>

So sts2mn should be adopted to unified output.

[Intelligent2013]

Done.