Basic matrix use introduction is missing in Rcpp

[juangomezduaso]

In the Outline (lines 30-33) of Rcpp.Rmd the use of a matrix class is anounced:

• Section @ref(rcpp-intro) teaches you how to write C++ by
  converting simple R functions to their C++ equivalents. You'll learn how
  C++ differs from R, and what the key scalar, vector, and matrix classes
  are called.

Later, line 93 promises to teach how to convert basic functions with

• Matrix input and vector output

But , as far as I can see, there is no more mention to matrices in all the section's text or examples
In section 25.6.1 ( Gibbs sampler. Line 821) there is an example using them as input and output, so I think their presence in the rcpp-intro section is missing.