Support Hugo template

[tadayosi]

As a memo, please support Hugo template style as follows:

# Why Camel?

{{< div "box right" >}}

{{< div "content">}}

## Based on Enterprise Integration Patterns

Camel supports most of the Enterprise Integration Patterns from the excellent book by Gregor Hohpe and Bobby Woolf, and newer integration patterns from microservice architectures to help you solve your integration problem by applying best practices out of the box.

Currently, even with --asciidoctor=false po files are generated like this:

#. type: Title #
#: upstream/content/_index.md:9
#, fuzzy, no-wrap
msgid "Why Camel?"
msgstr "なぜキャメルなのか？"

#. type: Plain text
#: upstream/content/_index.md:12 upstream/content/_index.md:53
#, fuzzy, no-wrap
msgid "{{< div \"box right\" >}}\n"
msgstr ""
"< div \"box right\" >{{}}\n"
"</div>"

#. type: Plain text
#: upstream/content/_index.md:14 upstream/content/_index.md:41
#: upstream/content/_index.md:55 upstream/content/_index.md:80
#, fuzzy, no-wrap
msgid "{{< div \"content\">}}\n"
msgstr ""
"< div \"content\">{{}}\n"
"</div>"

[tadayosi]

FYI, camel-ja project uses this script to workaround the issue.
https://github.com/jcug-oss/camel-ja/blob/main/bin/fix-hugo-template