Added docs

Author: suddendust

document-store/src/main/java/org/hypertrace/core/documentstore/expression/impl/DataType.java

@@ -22,6 +22,8 @@ public enum DataType {
   FLOAT,
   DOUBLE,
   BOOLEAN,
+  // timestamp with time-zone information. For example: 2004-10-19 10:23:54+02.
+  // For more info, see: https://www.postgresql.org/docs/current/datatype-datetime.html
   TIMESTAMPTZ,
   DATE
 }

document-store/src/main/java/org/hypertrace/core/documentstore/expression/impl/IdentifierExpression.java

@@ -73,6 +73,8 @@ public static IdentifierExpression ofBoolean(final String name) {
     return of(name, DataType.BOOLEAN);
   }
 
+  // Timestamp with time-zone information. For example: 2004-10-19 10:23:54+02. For more info, see:
+  // https://www.postgresql.org/docs/current/datatype-datetime.html
   public static IdentifierExpression ofTimestampTz(final String name) {
     return of(name, DataType.TIMESTAMPTZ);
   }