Adding the ability to change "Last Updated" field

This commit adds the ability to change the behavior of the "Last Updated"
field at the bottom of the html documents generated by asciidoc.
This will be done by using the "footer-style" new attribute.
This commit adds the ability to change it to the revision date or to skip it.

This commit also adds the documentation of this new feature to the user guide.

Testasciidoc tests are also provided in this commit.

1 files changed, 16 insertions, 0 deletions

diff --git a/doc/asciidoc.txt b/doc/asciidoc.txt
index fd33c61..e75ef2c 100644
--- a/doc/asciidoc.txt
+++ b/doc/asciidoc.txt
@@ -5965,6 +5965,22 @@ A short summary of changes in this document revision. Must be defined
 prior to the first document section. The document also needs to be
 dated to output this attribute.
 
+|footer-style |html4, html5, xhtml11 |
+Changes the "Last updated" field in the footer of the document or removes this
+field and the revision number (in the footer only). +
+Can take 3 values:
+
+- none : Don't display the "Last updated" and "Revision number" fields in the
+  footer of the document
+- revdate : The "Last updated" field's date in the footer will be the revision
+  date specified in the document (`revdate` attribute)
+- default (or any other value) : The "Last updated" field's date in the footer
+  will be the date of the input file modification
+
+This attribute can be set, for example, using `:footer-style: revdate` in the
+header of the file or using the `--attribute footer-style=revdate` command-line
+option.
+
 |scriptsdir |html5, xhtml11 |
 The name of the directory containing linked JavaScripts.
 See <<X35,HTML stylesheets and JavaScript locations>>.