Improve doc site left navbar structure
Improve doc site left navbar structure

I used git poorly and accidentally broke https://github.com/bazelbuild/bazel/pull/10775.

This is the continuation of that.

Fixes https://github.com/bazelbuild/bazel/issues/10792

Preview: https://htmlpreview.github.io/?https://github.com/gregestren/bazel-docsy/blob/master/content/Bazel%20Overview%20-%20Bazel%202.1.0.htm

Closes #10815.

PiperOrigin-RevId: 296305066

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