content: draft: reviewed -> managed (#1144)

The use of a change management tool doesn't necessarily indicate code
was reviewed. Perhaps it's simply requiring a PR to be used or a lint
checks to be run. 'managed' more precisely gets at what's happening.

fixes #1140

Signed-off-by: Tom Hennen <tomhennen@google.com>

docs/spec/draft/source-requirements.md

@@ -202,7 +202,7 @@ It MUST NOT be possible to modify the content of a branch without following its
 SLSA Source Level 2 ensures that all changes are recorded and attributable to an actor.
 SLSA Source Level 3 ensures that the documented process was followed.
 
-The change management tool MUST be able to authoritatively state that each new revision reachable from the protected branch represents only the changes reviewed via the process.
+The change management tool MUST be able to authoritatively state that each new revision reachable from the protected branch represents only the changes managed via the process.
 
 The change management tool MUST provide at a minimum: