DOC: Add a section for SW Guide example writing.

Add a section for writing examples used in the ITK Software Guide.

Although some overlap exists with the
[LaTeX README.md file](https://github.com/InsightSoftwareConsortium/ITKSoftwareGuide/blob/master/SoftwareGuide/Latex/README.md),
this was motivated by the constant build failures reported by CI builds,
and addressed for this time in:
http://review.source.kitware.com/#/c/23473/1

Also, emphasize the column limit in the mentioned `README` file.

Author: Jon Haitz Legarreta

SoftwareGuide/Latex/Appendices/CodingStyleGuide.tex

@@ -3747,6 +3747,62 @@ \subsection{Test Return Value}
 allowed in ITK.
 
 
+\section{Writing Examples}
+\label{sec:WritingExamples}
+
+Many ITK examples are used in this software guide to demonstrate ITK's
+architecture and development.
+
+Thanks to scripting work, parts of the \code{*.cxx} example files within
+special placeholders are included in this software guide. The \LaTeX
+placeholders available to the code for such purpose are:
+
+\begin{itemize}
+\item \textbf{Software Guide : BeginLatex} and
+\textbf{Software Guide : EndLatex}: the text within these placeholders is
+included in this software guide for text explanations, e.g.
+
+\small
+\begin{minted}[baselinestretch=1,fontsize=\footnotesize,linenos=false,bgcolor=ltgray]{cpp}
+//  Software Guide : BeginLatex
+//
+//  Noise present in the image can reduce the capacity of this filter to grow
+//  large regions. When faced with noisy images, it is usually convenient to
+//  pre-process the image by using an edge-preserving smoothing filter. Any of
+//  the filters discussed in Section~\ref{sec:EdgePreservingSmoothingFilters}
+//  could be used to this end. In this particular example we use the
+//  \doxygen{CurvatureFlowImageFilter}, so we need to include its header
+//  file.
+//
+//  Software Guide : EndLatex
+\end{minted}
+\normalsize
+
+\item \textbf{Software Guide : BeginCodeSnippet} and
+\textbf{Software Guide : EndCodeSnippet}: the text within these placeholders is
+included in this software guide for verbatim code snippets, e.g.
+
+\small
+\begin{minted}[baselinestretch=1,fontsize=\footnotesize,linenos=false,bgcolor=ltgray]{cpp}
+// Software Guide : BeginCodeSnippet
+#include "itkCurvatureFlowImageFilter.h"
+// Software Guide : EndCodeSnippet
+\end{minted}
+\normalsize
+
+\end{itemize}
+
+Note that anything inside these gets inserted into the document; avoid blank
+lines or too much whitespace. Make sure any \LaTeX comments included in the
+code are correct in terms of grammar, spelling, and are complete sentences.
+
+Note that \textbf{the code should not exceed 79 columns} or it will go out of
+margins in the final document.
+
+It is recommended that the \LaTeX comment blocks are aligned to the code for
+the sake of readability.
+
+
 \section{Doxygen Documentation System}
 \label{sec:DoxygenDocumentationSystem}
 

SoftwareGuide/Latex/README.md

@@ -46,7 +46,7 @@ Style Guidelines for the ITK Software Guide
   Anything inside these gets put into the document; avoid blank lines or too
   much whitespace. Make sure any comments in included code are correct in
   terms of grammar, spelling, and are complete sentences.
-  Note that the code should not exceed column 80 or it will go out of
+  Note that **the code should not exceed 79 columns** or it will go out of
   margins in the PDF document.
 
 7. Figure/table captions should be proper sentences and end in a period