misc: Merge 20.05.1, 19.08.3 RELEASE.md sections
misc: Merge 20.05.1, 19.08.3 RELEASE.md sections

also, remove a duplicate 17.01.1 section and wrong page tag for 20.09

Change-Id: Ia2cc77faa75cccab38972ad46517762cb7456466
Type: docs
Signed-off-by: Andrew Yourtchenko <eb6233fe2fbd585844f4fb8426b53b186ab379b1@gmail.com>

chrisy/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp