Add src/server/upstream.lisp to the ASD system definition.
Fix archive building.

The iolib to uiop conversion left errors in how archives files were
referenced, absolute pathnames were in use. Get back to normal by using
the `tar` command line tool to build the compressed archive file.
Fix API used to download an archive file in the C client.

We just got rid of the /api/fetch/:extension/:pgversion... entry so as
to be able to host archive files on any static web server, including AWS
S3 services, so update the C client code to use the new API instead.
Doc markdown syntax fix.

The Common Lisp markdown parser had a problem with two titles running
one just after the other without a blank line to keep them apart.