Remove call of ctx.saveChange() from example in plugin documentation
Remove call of ctx.saveChange() from example in plugin documentation

In change I3d8b13 this method was renamed to
ctx.bumpLastUpdatedOn(boolean). Calling it is no longer needed since
the default for bumping the last updated on timestamp was changed to
true by the same change.

Change-Id: Ia8a4dd844fdad077c1173f4707f1bfe86aec4729
Signed-off-by: Edwin Kempin <d43fb6c98c97e553b671ed9a9318100f1de386e7@google.com>
(cherry picked from commit 23033b634d70e338e1a5b837033bcdd003342df6)

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