Typo fix

Author: theoturner

Diff for: README.md

@@ -2,7 +2,7 @@
 
 A public blockchain + GUI allowing users to store and share information that can't be tampered with or repudiated.
 
-The architecture his based on the [IBM Blockchain](https://www.ibm.com/blockchain), however Proof of Work (PoW) is used as a consensus algorithm instead of IBM SE. The PoW structure is adapted from Kansal 2018 with SHA256 as the cryptographic hash function.
+The architecture is based on the [IBM Blockchain](https://www.ibm.com/blockchain), however Proof of Work (PoW) is used as a consensus algorithm instead of IBM SE. The PoW structure is adapted from Kansal 2018 with SHA256 as the cryptographic hash function.
 
 [Flask](http://flask.pocoo.org/) is used for the front end and is needed to run the app. Flask allows for RESTful interaction with nodes.