Doc: group backward-incompatible changes into sections
Doc: group backward-incompatible changes into sections

RELNOTES: None.
PiperOrigin-RevId: 217719080

dslomov/bazel-windows,cushon/bazel,aehlig/bazel,dslomov/bazel,dslomov/bazel-windows,bazelbuild/bazel,twitter-forks/bazel,aehlig/bazel,perezd/bazel,katre/bazel,meteorcloudy/bazel,twitter-forks/bazel,bazelbuild/bazel,bazelbuild/bazel,safarmer/bazel,werkt/bazel,ButterflyNetwork/bazel,ulfjack/bazel,werkt/bazel,dslomov/bazel-windows,ButterflyNetwork/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,akira-baruah/bazel,davidzchen/bazel,meteorcloudy/bazel,dslomov/bazel-windows,cushon/bazel,katre/bazel,aehlig/bazel,dslomov/bazel-windows,akira-baruah/bazel,ulfjack/bazel,twitter-forks/bazel,dslomov/bazel-windows,perezd/bazel,safarmer/bazel,dslomov/bazel,katre/bazel,twitter-forks/bazel,perezd/bazel,cushon/bazel,ulfjack/bazel,safarmer/bazel,perezd/bazel,cushon/bazel,akira-baruah/bazel,meteorcloudy/bazel,davidzchen/bazel,davidzchen/bazel,werkt/bazel,ButterflyNetwork/bazel,katre/bazel,perezd/bazel,cushon/bazel,dslomov/bazel,davidzchen/bazel,meteorcloudy/bazel,twitter-forks/bazel,meteorcloudy/bazel,perezd/bazel,bazelbuild/bazel,meteorcloudy/bazel,safarmer/bazel,ulfjack/bazel,ulfjack/bazel,katre/bazel,cushon/bazel,twitter-forks/bazel,perezd/bazel,ButterflyNetwork/bazel,ButterflyNetwork/bazel,werkt/bazel,safarmer/bazel,ulfjack/bazel,davidzchen/bazel,dslomov/bazel,werkt/bazel,davidzchen/bazel,ulfjack/bazel,akira-baruah/bazel,katre/bazel,akira-baruah/bazel,aehlig/bazel,werkt/bazel,aehlig/bazel,safarmer/bazel,aehlig/bazel,akira-baruah/bazel,dslomov/bazel,davidzchen/bazel,aehlig/bazel,dslomov/bazel,bazelbuild/bazel,dslomov/bazel,bazelbuild/bazel,twitter-forks/bazel