[Learnosm-coord] translation header

[althio forum]

Preliminary note/question:
The banner/header can be changed in the generic "_layouts/*.html" and
applied with "layout=*" in the desired file.
Is it possible to modify or simply add something to the banner/header
directly from a file without relying on layout in "_layouts/*.html"
and predefined text in "_config.yml"?


Here is the outline of what I was thinking of...
Tell me if it is suitable or broken from the start.
I may need Jeff's approval before I start something like this.


*** *** ***
In my page to-be-translated:

---
- layout: doc
+ layout: doc-translating
...
- lang: en
+ lang: fr
---



*** *** ***
In learnosm/_layouts/doc-translating.html

---
layout: doc
---

    <div id='header' class='cell12'>
      <div class='marginL cell9 padAll'>
        <div class='cell7 marginR'>
           <span><a href='{{site.baseurl}}/{{page.lang}}' class="logo
logo-learn"></a></span>
           <span
class='tagline'>{{site.translations.[page.lang].tagline}}</span>
        </div>
        <a class='banner hide-mobile'>
          <span
class='{{page.lang}}'>{{site.translations.[page.lang].contribute}}</span>
        </a>
        <a class='banner-mobile hide-desktop show-mobile'
href='{{site.baseurl}}/{{page.lang}}/contribute/'>
        </a>
+        <div class='***********'>
+           <span><a href='{{site.baseurl}}/{{page.lang}}' class="***
image 'works in progress' ***"></a></span>
+           <span
class='translating'>{{site.translations.[page.lang].translating}}</span>
+        </div>
      </div>
    </div>
    <div id='content' class='cf'>
        {{ content }}
    </div>



*** *** ***
In learnosm/_config.yml

translations:
  en:
    tagline: "Learn OpenStreetMap Step by Step"
    ...
    getstarted: "Get started"
+    translating: "This section of LearnOSM is in the process of being
translated. If you would like to assist with translating this site,
please see [CONTRIBUTING.md](https://github.com/hotosm/learnosm/blob/gh-pages/CONTRIBUTING.md)."
 ...
  fr:
    tagline: "Apprendre OpenStreetMap pas à pas"
    ...
    getstarted: "Commencer"
+    translating: "Cette page de LearnOSM est en cours de traduction.
Si vous voulez aider pour d'autres pages, rendez-vous sur
[CONTRIBUTING.md](https://github.com/hotosm/learnosm/blob/gh-pages/CONTRIBUTING.md)."
...