Prefixes of `Docfile.name` are inconsistent

[wtsnjp]

Docfile.name is a name of doc file only used for scoring. Their prefixes are inconsistent and probably depend on the sources of a docfile information (i.e., either from tlpdb or texdocs).

• Case 1: the name starts from texmf-dist

texdoc/spec/search/tlpdb_spec.rb

Line 27 in 6fec041

let(:test_res_name) { "texmf-dist/doc/man/man1/dvipdfmx.man1.pdf" }

• Case 2: the name starts from the dirname under the texmf-dist/doc tree

texdoc/spec/search/tlpdb_spec.rb

Line 8 in 6fec041

let(:test_res_name) { "latex/babel/babel.pdf" }

The inconsistency is harmless for the function right now, but is slightly troublesome for testing and debugging.