Some proposals for small fixes

[christofs]

Just some things I came across:

Fix link to source of scans (double http):

<ref>http://https://polona.pl/item/bialy-murzyn-powiesc,Njc4NTgwODg/6/#info</ref>

Fix language indicator (has not been inserted):

<ref type="doi" target="https://doi.org/10.5281/zenodo.4662595">ELTeC-$textLang</ref>
<ref type="doi" target="https://doi.org/10.5281/zenodo.4662725">ELTeC-$textLang release 1.0.0</ref>

Add <bibl type="firstEdition"> even when this seems redundant and add the year of first publication. It may differ from the date in "printSource"! Like so, after the other two bibl entries.

<bibl type="firstEdition">
<date>1875</date>
</bibl>