Fix best-practives.rst:
     1. Line 89 code not highlight.
     2. The End of doc miss as follows.
Fix private-data-arch.rst:
     1. Line 214 word order error.

Change-Id: I9ef91c72550cc1a6e9aafaecc617772901bf7b50
Signed-off-by: TopJohn <xzj19922010@gmail.com>
(cherry picked from commit db68f57605b4c6929193a1b73e4e42b51173b0f4)