Improve transcript documentation (translator experience)

I ping here @RetSamys , @martindisch and @gunchleoc to just let you know I opened this thread. I plan to make those improvements (I'm not puting any TODO on your back or expect anything). Oc course, If you are interested into it; I'll welcome any help and feedback! Feel free to take initiatives. If I do something, it will by the end February anyway; I have a big priority on the future episode 34 right now.

So here are my ideas for improving transcript (translator experience), feel free to also add ideas and items :

1. Better header for transcript files

In the header of the transcripts markdown files (the one already made and hosted on webcomics repo), put a short reminder this markdown file can be semi auto-generated after completing the translation of the SVG. Do not assume the translators will follow the link to the documentation to write this information. Let's assume they'll open the markdown text-file (the one they get after usually duplicate the 'en' folder of the episode) and perceive this file as something they need to manually edit. That's why this additional information in the header have to tell them the repo CI offers tools for that and it's not something to be done manually.

The header right now:

## Notes

Providing transcripts is optional for translators.
The Pepper&Carrot site will work fine without them,
but they help for accessibility, screen readers and language learners.

Read https://www.peppercarrot.com/en/static14/documentation&page=062_Transcripts
for more information and documentation.

a proposal (a single line added):

## Notes

Providing transcripts is optional for translators.
The Pepper&Carrot site will work fine without them,
but they help for accessibility, screen readers and language learners.

+ Tools exists to generate this file after you are done translating the 
speechbubbles of the SVG. Read:
https://www.peppercarrot.com/en/static14/documentation&page=062_Transcripts
for more information and documentation.

2. Documentation

https://www.peppercarrot.com/en/static14/documentation&page=062_Transcripts can probably receive improvement to be written for the point of view of a translator who use Gitlab via GUI to upload SVG. At least, located on the top part of the documentation with screenshots (this part is actually on the bottom of the page). We can keep the bottom for advanced user knowing Python and using Git with terminal. An idea: a tiny video (screencast of a webbrowser video; less or around 720p) with voice and subtitle could help to get an overview of the process.

Thread with references to this issue:

ref: webcomics#175 (closed) ref: !13 (merged) ref: webcomics!695 (merged)