Merge "docs: Fixed "known issues" link." into mnc-mr-docs

  <li> <a href="https://code.google.com/p/android-developer-preview/">N Developer Preview Issue

    Tracker</a> is your <strong>primary feedback channel.</strong> You can report bugs, performance

    issues, and general feedback through the issue tracker. You can also check for

<a href="{@docRoot}preview/bug">known issues</a> and

<a href="{@docRoot}preview/bugs">known issues</a> and

    find workaround steps. We’ll keep you updated on your issue as it’s triaged and sent to

    the Android engineering team for review. </li>

  <li> The <a href="{@docRoot}preview/dev-community">Android N Developer Community</a> is