Generated documentation for `Lems` root element does not include `Include`

[sanjayankur31]

As title. Can be confirmed in the generated docs:

http://lems.github.io/LEMS/elements.html

The paper also notes that Lems should have Include (see figure 2 also).

[sanjayankur31]

I see that this is included separately in the doc generation: https://github.com/LEMS/LEMS/blob/master/docgeneration/docsrc/elements.xml#L22

I'll add it manually to the neuroml docs too, for the time being.

[sanjayankur31]

Done in NeuroML/Documentation@3b03e60