add comments

src/main/java/gov/usgs/earthquake/nshmp/internal/LibVersion.java

@@ -3,7 +3,9 @@ package gov.usgs.earthquake.nshmp.internal;
 import com.google.common.io.Resources;
 
 /**
+ * Read in and return nshmp-lib-version.json.
  *
+ * File is create from Gradle on build.
  */
 public class LibVersion implements AppVersion {