gitignore: Allow README.txt, disallow README-wear.txt

- README.txt is no longer autogenerated.
- README-wear.txt has been added to the "wear" teamplate and should
- be ignored.

Change-Id: Ic48b4f658db2a1d99ac2e487192e8d08eb79387f
(cherry picked from commit da1fc6fbb36422b12dbd9cbd19cbbc7b375cd087)
1 file changed