Fix freemarker site urls
Change some external urls, available with https.
diff --git a/src/main/docgen/book.xml b/src/main/docgen/book.xml
index 1b3d147..7ef4ae0 100644
--- a/src/main/docgen/book.xml
+++ b/src/main/docgen/book.xml
@@ -275,7 +275,7 @@
2.2 series. Requires J2SE 1.2 or higher.</para>
<para><link
- xlink:href="http://prdownloads.sourceforge.net/freemarker/freemarker-2.2.8.tar.gz">Download
+ xlink:href="https://prdownloads.sourceforge.net/freemarker/freemarker-2.2.8.tar.gz">Download
freemarker-2.2.8.tar.gz</link> (1.4 MB)</para>
</simplesect>
@@ -286,7 +286,7 @@
2.1 series. Requires J2SE 1.3 or higher.</para>
<para><link
- xlink:href="http://prdownloads.sourceforge.net/freemarker/freemarker-2.1.5.tar.gz">Download
+ xlink:href="https://prdownloads.sourceforge.net/freemarker/freemarker-2.1.5.tar.gz">Download
freemarker-2.1.5.tar.gz</link> (909 KB)</para>
</simplesect>
@@ -297,7 +297,7 @@
series. Requires J2SE 1.2 or higher.</para>
<para><link
- xlink:href="http://prdownloads.sourceforge.net/freemarker/freemarker2_03.tar.gz">Download
+ xlink:href="https://prdownloads.sourceforge.net/freemarker/freemarker2_03.tar.gz">Download
freemarker2_03.tar.gz</link> (617 KB)</para>
</simplesect>
@@ -315,7 +315,7 @@
<para>Outdated versions starting from 2.3.24 RC01 are available from the
Apache archive: <link
- xlink:href="http://archive.apache.org/dist/incubator/freemarker/engine/">http://archive.apache.org/dist/incubator/freemarker/engine/</link>.
+ xlink:href="https://archive.apache.org/dist/incubator/freemarker/engine/">https://archive.apache.org/dist/incubator/freemarker/engine/</link>.
Even older releases are available from the <link
xlink:href="https://sourceforge.net/projects/freemarker/files/freemarker/">SourceForge
download page</link>.</para>
