doc/lsjd_endpoints.md: Changes in author and signature fields
doc/lsjd_endpoints.md: Changes in author and signature fields

- author changed to authorkey needs to send the publicy key in
base64 encoding
- singature specified to use base64 enconding

Signed-off-by: Anibal Limon <b5f0f822327db62ed599ac923b570c6baf81f31f@gmail.com>

hsmty/LibreScienceJournal