Update index.md
Update index.md

The first sentence in step 6 read "To make your Docker swarm and UCP fault-tolerant and highly available, you can join more manager nodes to your it."
LuisBosquez/docker.github.io,shubheksha/docker.github.io,docker/docker.github.io,LuisBosquez/docker.github.io,docker/docker.github.io,docker-zh/docker.github.io,thaJeztah/docker.github.io,docker-zh/docker.github.io,thaJeztah/docker.github.io,bdwill/docker.github.io,joaofnfernandes/docker.github.io,docker-zh/docker.github.io,JimGalasyn/docker.github.io,bdwill/docker.github.io,joaofnfernandes/docker.github.io,shubheksha/docker.github.io,JimGalasyn/docker.github.io,phiroict/docker,LuisBosquez/docker.github.io,bdwill/docker.github.io,anweiss/docker.github.io,shin-/docker.github.io,londoncalling/docker.github.io,shin-/docker.github.io,joeuo/docker.github.io,joeuo/docker.github.io,JimGalasyn/docker.github.io,phiroict/docker,bdwill/docker.github.io,LuisBosquez/docker.github.io,docker-zh/docker.github.io,johnstep/docker.github.io,johnstep/docker.github.io,thaJeztah/docker.github.io,phiroict/docker,thaJeztah/docker.github.io,docker/docker.github.io,johnstep/docker.github.io,shin-/docker.github.io,shubheksha/docker.github.io,docker/docker.github.io,shin-/docker.github.io,joaofnfernandes/docker.github.io,londoncalling/docker.github.io,joeuo/docker.github.io,joaofnfernandes/docker.github.io,joaofnfernandes/docker.github.io,JimGalasyn/docker.github.io,docker/docker.github.io,johnstep/docker.github.io,londoncalling/docker.github.io,thaJeztah/docker.github.io,anweiss/docker.github.io,anweiss/docker.github.io,shubheksha/docker.github.io,JimGalasyn/docker.github.io,bdwill/docker.github.io,docker-zh/docker.github.io,londoncalling/docker.github.io,anweiss/docker.github.io,LuisBosquez/docker.github.io,joeuo/docker.github.io,johnstep/docker.github.io,londoncalling/docker.github.io,phiroict/docker,anweiss/docker.github.io,shin-/docker.github.io,shubheksha/docker.github.io,joeuo/docker.github.io,phiroict/docker