doc: add report version section

Author: legendecas

doc/api/report.md

@@ -601,6 +601,8 @@ includes the date, time, PID, and a sequence number. The sequence number helps
 in associating the report dump with the runtime state if generated multiple
 times for the same Node.js process.
 
+## Report Version
+
 Diagnostic report has an associated single-digit version number (`report.header.reportVersion`),
 uniquely representing the report format. The version number is bumped
 when new key is added or removed, or the data type of a value is changed.