Brew Install encounter error /usr/local/share/texinfo is not writable

==> Installing ffmpeg dependency: texi2html
==> Downloading https://homebrew.bintray.com/bottles/texi2html-5.0.high_sierra.b
==> Downloading from https://akamai.bintray.com/52/5259ab2074f122f4725058d247723
######################################################################## 100.0%
==> Pouring texi2html-5.0.high_sierra.bottle.1.tar.gz
Error: The `brew link` step did not complete successfully
The formula built, but is not symlinked into /usr/local
Could not symlink share/texinfo/html
/usr/local/share/texinfo is not writable.

any ideas?