Incorrect location for undocumented Core methods

[d-torrance]

For example:

i1 : locate makeDocumentTag (sin, Number)

o1 = /usr/share/Macaulay2/typicalvalues.m2:271:0

o1 : FilePosition

That file doesn't exist! It should be /usr/share/Macaulay2/Core/typicalvalues.m2.

I think the problem is that we call undocumented on this method in Core, but makeDocumentTag changes the package to Macaulay2Doc, messing up the path.