[R-wiki] Wiki and R namespaces

[Henrik Bengtsson]

More feedback:

The word 'namespace' will most certainly be confusing in the R-wiki. 
When I went to "rdoc" to see help on R functions, I though
"namespaces" referred to R namespaces and that the sentence "This is
an index over all available pages ordered by namespaces" was simply a
mistake.  Then I saw the same on the front page and realized my
mistake.

I think it is clearer write "Wiki namespaces" or even "Wiki (not R)
namespaces" whereever using the word.

/Henrik