[README] Warn about root installation issues

Mitigates #1151.

Author: VWoeltjen

README.md

@@ -17,6 +17,7 @@ Differences between the two APIs include a move away from a declarative system o
 ## Building and Running Open MCT Locally
 
 Building and running Open MCT in your local dev environment is very easy. Be sure you have [Git](https://git-scm.com/downloads) and [Node.js](https://nodejs.org/) installed, then follow the directions below. Need additional information? Check out the [Getting Started](https://nasa.github.io/openmct/getting-started/) page on our website.
+(These instructions assume you are installing as a non-root user; developers have [reported issues](https://github.com/nasa/openmct/issues/1151) running these steps with root privileges.)
 
 1. Clone the source code