XML: change doctype values

[Intelligent2013]

Using of XSLTs modules depends on content of doctype XML element. To prevent of further issues in command line calls due names with space chars, upper cases, etc. need to change doctype to more short values.

Non-correct values found here:

• mpfd-bpn, mpfd-compliance:

<doctype>Supervision of MPF Intermediaries</doctype>

• mpfd-guidelines:

<doctype>Guidelines</doctype>

• mpfd-standards:

<doctype>Compliance Standards for MPF Trustees</doctype>

Source: metanorma/mn-native-pdf#162 (comment)

[opoudjis]

Doctype was entered into MPF samples as free text. Given that this is a proof of concept gem with zero analysis, there is no controlled vocabulary for MPFA documents. It is also clear that uppercase characters and spaces need to be excluded from doctype, if they haven't been already; ruling them as invalid is not going to be enough, given the downstream implications identified here. So doctype needs to be normalised before it even gets validated.

[opoudjis]

Need to use doctype() as an accessor function throughout Metanorma.