Moving \SweaveOpts to after \begin{document}

When compiling on RStudio, I had to have the
\SweaveOpts{concordance=TRUE} command after the \begin{document} because
it appears that in the tex file produced the \usepackage{Sweave} command
is placed right before the \begin{document}
Fixed typos

Really just tiny typos, nothing important.
Fixed typos, including in eqns. (3.4) and (3.9)

Trivial corrections, except perhaps in eqns (3.4) and (3.9)
Revert "Moving \SweaveOpts to after \begin{document}"

This reverts commit 6f2cfbb2a948fa5350b72ba79275cc38da5b8fae.
Merge pull request #1 from gustavdelius/Updated-vignette

Fixing some typos in the vignette