Fix typo in VpnManager Docs.

Bug: 153364039
Test: n/a. Docs change only.
Change-Id: I8259bfc09735515f428bb41d69fedd3ea1961f79
Merged-In: I8259bfc09735515f428bb41d69fedd3ea1961f79
(cherry picked from commit 3150b04b67dc75fe5edebad6870fc09710d07af2)
1 file changed