docs: remove the HARDWRAPS generation option

Motivation:

The HARDWRAPS option introduces the possibility to split content into
multiple lines where a line break in the input file result in a line
break in the HTML output.

For example, an input markdown file containing:

    line 1
    line 2
    line 3

With HARDWRAPS the HTML output will show three separate lines.  Without
this option, the three lines are joined together as part of a single
paragraph.

Github markdown flavour joins these lines together; moreover, our
current documentation is written assuming that lines may be broken
between any two adjacent words within a paragraph without affecting the
output.

Therefore, generating output with HARDWRAPS results in HTML output with
unexpected and ugly line breaks.

Modification:

Remove the HARDWRAPS option.

Result:

Output more closely matches github rendered HTML.

Target: master
Patch: https://rb.dcache.org/r/11406/
Acked-by: Albert Rossi

docs/TheBook/pom.xml

@@ -41,7 +41,7 @@
             <headerHtmlFile>${html-header.path}</headerHtmlFile>
             <footerHtmlFile>${html-footer.path}</footerHtmlFile>
             <transformRelativeMarkdownLinks>true</transformRelativeMarkdownLinks>
-            <pegdownExtensions>SMARTYPANTS,HARDWRAPS,AUTOLINKS,TABLES,FENCED_CODE_BLOCKS,STRIKETHROUGH,TASKLISTITEMS,EXTANCHORLINKS</pegdownExtensions>
+            <pegdownExtensions>SMARTYPANTS,AUTOLINKS,TABLES,FENCED_CODE_BLOCKS,STRIKETHROUGH,TASKLISTITEMS,EXTANCHORLINKS</pegdownExtensions>
             <copyDirectories>css,images</copyDirectories>
           </configuration>
       </plugin>