[Rd] Typo in R-lang (PR#6897)

[arnima at u.washington.edu]

I believe there's a typo in the R Language Definition 1.9.0 (2004-04-12)
draft. Around the middle of subsection 5.1 it says:

 ... a final search for foo.default would be made

This should probably be:

 ... a final search for mean.default would be made

Cheers,
Arni