Adding Copyrights on text files

Dear @xdraho11,

I analysed the current code and found that copyright headers were missing from the majority of text files.
I have produced a Pull Request to show mainly the type of headers we expect when IP Reviewing open source code.
I invite you to check each change because in some cases, for example in the html files, I noticed that they contained cut code and I suspect that it could be injected into a larger file.
You'll notice that I've assigned ownership to bAvenir. If this is not the correct name or owner, please let me know and I will correct it. Use this PR issue for this.

Feel free to be inspired and/or accept the whole PR.

I still need to produce headers on some missing files, mainly json files.

Thx a lot

/cc @davidremon