Update the URL of the about page in the the readme files

[takavarasha]

The url of the about page in the readme files has changed. The new URL in data.hdx.rwlabs.org/about

[cjhendrix]

Update:

Note, the current URL in these files leads to the blog, which is not an unreasonable place for them to go. However, when we have time to change this, the desired change is:

In the readme.txt and readme tab of the xlsx exports, change http://docs.hdx.rwlabs.org/
to
data.hdx.rwlabs.org/about

The URL to be changed is on line 4 in both files.