ERROR: RDoc documentation generator not installed!

i am installing rails on a new machine, and during each of my gem installs, i am getting this:

1 gem installed ERROR: While executing gem ... (Gem::DocumentError)     ERROR: RDoc documentation generator not installed!

anyone have any ideas?

yum install ruby-docs

I just found this old thread searching for the same problem. For me, the actual needed command was 'yum install ruby-rdoc'