Update and rename ChangeLog to ChangeLog.md

[CGarces]

Data fetch from https://www.httrack.com/page/4/en/index.html

[Neustradamus]

@CGarces: Normally when you rename a file it is specified:
ChangeLog->ChangeLog.md

[Neustradamus]

@xroche: It is possible to merge this PR?

[CGarces]

Wow, 2020 I totally forget this.
After review 70d43d4 I realize that the information already exist on history.txt

So looks like a better option:

• Delete ChangeLog
• Optionally rename history.txt to ChangeLog.md

[xroche]

Declining this one: history.txt is the maintained changelog, and the empty ChangeLog is only an automake stub (now a symlink to history.txt), so a second changelog would just drift. Thanks anyway.