Formatting updates to correct errors in documentation builds

Formatting anomalies in db2.adoc and cloudevents.adoc are causing unexpected results in the built documentation.

In the Db2 doc, extra anchor IDs in the metrics section prevent subtopic files from being generated downstream, resulting in linking errors.

In the CloudEvents file, links in the table of converter configuration options fail due to improper formatting. The anchor ID for each table entry precedes the cell delimiter, rather than being placed within the cell.