#12 Migrate from master to main (#13)

Author: docktermj

CONTRIBUTING.md

@@ -115,7 +115,7 @@ TODO:
 
 ### Pull Requests
 
-Code in the master branch is modified via GitHub pull request.
+Code in the main branch is modified via GitHub pull request.
 Follow GitHub's
 [Creating a pull request from a branch](https://help.github.com/articles/creating-a-pull-request/)
 or

README.md

@@ -23,7 +23,7 @@ ElasticSearch itself is a separate software product, not made by Senzing.  You m
 ### Create SENZING_DIR for the G2 engine
 
 If you do not already have an `/opt/senzing` directory on your local system, visit
-   [HOWTO - Create SENZING_DIR](https://github.com/Senzing/knowledge-base/blob/master/HOWTO/create-senzing-dir.md).
+   [HOWTO - Create SENZING_DIR](https://github.com/Senzing/knowledge-base/blob/main/HOWTO/create-senzing-dir.md).
 
 ### Add the G2 interface for ElasticSearch to your Senzing installation