Format error in doc for topic routing and event flattening SMTs

In the master version of the doc for the event flattening SMT, the heading in the configuration properties table looks like this for the third column: 

You can see this here: https://debezium.io/documentation/reference/configuration/event-flattening.html#configuration-options 

The topic routing SMT doc has a similar error. These errors are only in master.

Earlier, I updated formats for these two SMTs in DBZ-2554 and this is the PR for that issue:

https://github.com/debezium/debezium/pull/1819

That PR needs to be backported to 1.3. When it is, these errors will show up in the 1.3 published doc. I think, but I am not sure, that this error is caused by the way the table columns are declared. The table column declaration is updated in master but not in the 1.3 branch. 

So the work for this Jira is to update the topic routing SMT file and the event flattening SMT file so that the third column heading renders correctly. I'll do this in master.  Then PR 1819 needs to be backported to master, and the PR for this Jira also needs to be backported to master. 

This error does NOT appear downstream in the published Q3 doc. I think I fixed it downstream.