V1.0.2: Updated typos in Readme files

Minor update to correct typos in readme files and link them all to the master readme file.

To get the latest version of this repository onto your local system, assuming that you have followed the recommendation to first fork this repository and then clone from your own id, issue the two following commands.
The first command tells git to use this repository as the upstream master. You only need execute this command once during the life of your local cloned repository.

git remote add upstream https://github.com/rddill-IBM/ZeroToBlockchain.git

The second command tells git to retrieve the latest information from the upstream master and integrate it into your local, cloned copy

git pull upstream master