Add demo link to README

Author: thatbudakguy

readme.md

@@ -3,7 +3,7 @@
 
 # OpenGeoMetadata Viewer
 
-A web-based viewer for previewing [OpenGeoMetadata](https://opengeometadata.org/) records.
+A web-based viewer for previewing [OpenGeoMetadata](https://opengeometadata.org/) records. Try the [online demo](http://opengeometadata.org/ogm-viewer/)!
 
 ## Installation
 
@@ -102,4 +102,4 @@ npm run build
 npm publish
 ```
 
-You can create a new release on GitHub by going to the "Releases" section and clicking "Draft a new release". The "Generate release notes" option will automatically include the changes since the last tag.
+You can create a new release on GitHub by going to the "Releases" section and clicking "Draft a new release". The "Generate release notes" option will automatically include the changes since the last tag.