correct title level inconsistency

source/installation.rst

@@ -486,7 +486,7 @@ If you’ve made it this far, congratulations! Now it’s time to start processi
    :align: center
 
 Running on more than one machine
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 **Optionally:** If you have another computer, you can repeat the installation process (install docker, git, python, etc.) and launch a new NodeODM node by typing from a Terminal/Git Bash window: