requirements: Limit Markdown to < 3.0
requirements: Limit Markdown to < 3.0

We are not compatible with higher versions of Markdown.

Signed-off-by: Fam Zheng <df9fd617995bad07eac70e27aa3fe5069270e3bd@redhat.com>
Message-Id: <20181030100503.26278-2-df9fd617995bad07eac70e27aa3fe5069270e3bd@redhat.com>
Signed-off-by: Paolo Bonzini <69d3ebcf5ee4e7f05a50dc23cd96655b730804b4@redhat.com>

patchew-project/patchew,patchew-project/patchew,patchew-project/patchew,patchew-project/patchew