[ruby-core:67803] Add sho-h as committer

Hello!

I'd like to add Sho Hashimoto as a committer. He will help me with
documentation commits, and keep rurema in sync with trunk.

Sho is top committer to rurema documentation project, and has been doing a
great job:
https://github.com/rurema/doctree/commits?author=sho-h

You can see his endless amount of contributions there, and other Ruby
projects in the community on github: https://github.com/sho-h

Sho's redmine account is here:https://bugs.ruby-lang.org/users/129

May the Ruby be with you!
<3 <3 <3 <3