update URL so .md file can be properly displayed on a browser

Author: wkliao

wiki/Download.html

@@ -49,14 +49,14 @@
  </tr>
  <tr>
    <td align=center>December 19, 2018</td>
-   <td align=center><a href=../Release_notes/1.11.0.md>1.11.0</a></td>
+   <td align=center><a href=https://github.com/Parallel-NetCDF/Parallel-NetCDF.github.io/blob/master/Release_notes/1.11.0.md>1.11.0</a></td>
    <td><a href="../Release/pnetcdf-1.11.0.tar.gz" onClick="var that=this; ga('send', 'event', 'PnetCDF', 'Source Download (GZ)', 'pnetcdf-1.11.0.tar.gz', 1); ga('pnetcdfTracker.send', 'event', 'PnetCDF', 'Source Download (GZ)', 'pnetcdf-1.11.0.tar.gz', 1); ga('parallelnetcdfTracker.send', 'event', 'PnetCDF', 'Source Download (GZ)', 'pnetcdf-1.11.0.tar.gz', 1); setTimeout(function(){location.href=that.href;},500); return false;">pnetcdf-1.11.0.tar.gz</a></td>
    <td>2.1 MB</td>
    <td>a13fd24953abce1f3fd7aa94fd66f1b9895182de</td>
  </tr>
  <tr>
    <td align=center>July 2, 2018</td>
-   <td align=center><a href=../Release_notes/1.10.0.md>1.10.0</a></td>
+   <td align=center><a href=https://github.com/Parallel-NetCDF/Parallel-NetCDF.github.io/blob/master/Release_notes/1.10.0.md>1.10.0</a></td>
    <td><a href="../Release/parallel-netcdf-1.10.0.tar.gz" onClick="var that=this; ga('send', 'event', 'PnetCDF', 'Source Download (GZ)', 'parallel-netcdf-1.10.0.tar.gz', 1); ga('pnetcdfTracker.send', 'event', 'PnetCDF', 'Source Download (GZ)', 'parallel-netcdf-1.10.0.tar.gz', 1); ga('parallelnetcdfTracker.send', 'event', 'PnetCDF', 'Source Download (GZ)', 'parallel-netcdf-1.10.0.tar.gz', 1); setTimeout(function(){location.href=that.href;},500); return false;">parallel-netcdf-1.10.0.tar.gz</a></td>
    <td>2.0 MB</td>
    <td>9ac144f305e14ae6306f5e51af1b4329bfb86480</td>