Update README.md for header-checker.

Bug: 64267858

Test: N/A

Merged-In: Ic16283c535fc31ef53c009749cef88f258808f8c
Change-Id: Ic16283c535fc31ef53c009749cef88f258808f8c
(cherry picked from commit 233841f2fef249ac6fe81e94739f7a01afea55ac)
1 file changed