Merge pull request #159 from mcode/node-version-readme-update

README specifies a concrete node version number

Author: jafeltra

README.md

@@ -29,7 +29,8 @@ A Node.js framework for extracting mCODE FHIR resources. All resources are profi
 
 ## Prerequisites
 
-- [Node.js >= 12](https://nodejs.org/en/)
+- [Node.js v14.18.1 (LTS as of Oct 2021)](https://nodejs.org/en/)
+  - npm v6.14.15 (included in LTS of Oct 2021)
 
 ### Latest