Errors building documentation

[cgay]

When gendoc builds the docs for binary-data it gets these warnings:

/tmp/tmp.UxWt0ITlBP/gendoc/docs/source/binary-data/index.rst:28: WARNING: download file not readable: /tmp/tmp.UxWt0ITlBP/gendoc/docs/source/papers/a-DSL-for-manipulation-of-binary-data.pdf
/tmp/tmp.UxWt0ITlBP/gendoc/docs/source/binary-data/index.rst:29: WARNING: download file not readable: /tmp/tmp.UxWt0ITlBP/gendoc/docs/source/papers/secure-networking.pdf
/tmp/tmp.UxWt0ITlBP/gendoc/docs/source/binary-data/reference.rst:966: ERROR: Unknown target name: "<byte> https://opendylan.org/library-reference/common-dylan/byte-vector.html#common-dylan:byte-vector:[byte]".