add tags to README & update tags description

Author: dccakes

docs/README.md

@@ -59,7 +59,7 @@ description:
   limitations: null
   usage: null
 
-tags: null
+tags: ['finance']
 ```
 
 ### Definitions
@@ -112,7 +112,7 @@ schema:
         type: businessDefinition
       - url: https://youtu.be/jbY1BKFj9ec
         type: videoTutorial
-    tags: null
+    tags: ['finance']
     dataGranularityDescription: Aggregation on columns txn_ref_dt, pmt_txn_id
     properties:
       - name: txn_ref_dt
@@ -222,7 +222,7 @@ schema:
 | businessName             | Business Name                | No       | The business name of the element.                                                                                                                                                                                      |
 | authoritativeDefinitions | Authoritative Definitions    | No       | List of links to sources that provide more details on the table; examples would be a link to an external definition, a training video, a GitHub repo, Collibra, or another tool. See `authoritativeDefinitions` below. |
 | quality                  | Quality                      | No       | List of data quality attributes.                                                                                                                                                                                       |
-| tags                     | Tags                         | No       | A list of tags that may be assigned to the elements (object or property); the tags keyword may appear at any level.                                                                                                    |
+| tags                     | Tags                         | No       | A list of tags that may be assigned to the elements (object or property); the tags keyword may appear at any level. Tags may be used to better categorize an element. For example, `finance`, `sensitive`, `employee_record`.                                                                                          |
 | customProperties         | Custom Properties            | No       | Custom properties that are not part of the standard.                                                                                                                                                                   |
 
 #### Applicable to Objects