1.0: Use `{% include %}` directive for footer content

[kenhys]

Problem

If we need to modify footer content in each page, we should also modify ~170 page files.
It seems better to split it into a separate file.

I've tried to use {% include %} with #322.
It works in local environment, but when it was reverted even though it was merged once.
(I've heard that it was not worked as expected 😞 )

Expected

To keep mainteinanability, use {% include %} or something good alternative for docs.fluentd.org.

Additional Information

I've tested with the following version.

% gitbook --version
CLI version: 2.3.2
GitBook version: 3.2.3

[kenhys]

Hmm, https://gitbookio.gitbooks.io/documentation/content/format/conrefs.html
I've deployed test space, but Importing local files does not work on gitbook.io

[kenhys]

It seems that it is marked as planning status:
https://gitbook.canny.io/feature-requests/p/support-for-footers

[kenhys]

I've overlooked that it seems GitBook v2 (not v1)
https://docs.gitbook.com/resources/gitbook-legacy/v2-differences