doc: Add GitHub issue template
doc: Add GitHub issue template

Signed-off-by: Thomas Graf <5f50a84c1fa3bcff146405017f36aec1a10a9e38@cilium.io>

tklauser/cilium,tgraf/cilium,cilium/cilium,scanf/cilium,tgraf/cilium,michi-covalent/cilium,tklauser/cilium,scanf/cilium,michi-covalent/cilium,tklauser/cilium,cilium-team/cilium,scanf/cilium,cilium/cilium,scanf/cilium,tgraf/cilium,scanf/cilium,cilium/cilium,tklauser/cilium,tgraf/cilium,eloycoto/cilium,tgraf/cilium,tgraf/cilium,michi-covalent/cilium,eloycoto/cilium,eloycoto/cilium,tklauser/cilium,cilium/cilium,eloycoto/cilium,cilium-team/cilium,eloycoto/cilium,eloycoto/cilium,scanf/cilium,scanf/cilium,michi-covalent/cilium,eloycoto/cilium,cilium/cilium,michi-covalent/cilium