GeezerVison

fixes #63.

add an indexed intelhex.hex2bin function reference to the writing-data section, covering filenames/streams, the inclusive address range, size precedence, padding, and return/error behavior. link the hex2bin.py script page to that reference and include an in-memory conversion example.

validation: sphinx 8.2.3 builds the full manual with the same existing static-directory warning and no new ones. the function anchor is absent before the change and present afterward; the script page links to it. all six example doctest steps pass. git diff --check passes.