docs: sphinx: Fix couple of spellings in the file rstFlatTable.py

s/automaticly/automatically/
s/buidler/builder/

..and a sentence construction fix.

Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20210301201052.11067-1-unixbhaskar@gmail.com


Signed-off-by: Jonathan Corbet <corbet@lwn.net>