go/packages: remove obsolete comment about LoadMode in doc.go

The comment referred to each mode returning more data about previous modes,
which was true about the old LoadMode hierarchy, but doesn't apply to the
new bits system.

Updates golang/go#35872

Change-Id: Id8354f49fdebcb231df8e5ece58644a29d678e4a
Reviewed-on: https://go-review.googlesource.com/c/tools/+/209977
Run-TryBot: Michael Matloob <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Brad Fitzpatrick <[email protected]>

Author: matloob

go/packages/doc.go

@@ -60,8 +60,7 @@ causes Load to run in LoadFiles mode, collecting minimal information.
 See the documentation for type Config for details.
 
 As noted earlier, the Config.Mode controls the amount of detail
-reported about the loaded packages, with each mode returning all the data of the
-previous mode with some extra added. See the documentation for type LoadMode
+reported about the loaded packages. See the documentation for type LoadMode
 for details.
 
 Most tools should pass their command-line arguments (after any flags)