avoid messing up changelog history on each subsequent release

[timotheecour]

• I've updated and simplified the changelog instructions
  instead of destroying changelog history (eg git blame etc) on each release by moving changelog.md to changelog_x_y_z.md and replacing changelog.md upon each release, we are now directly writing changelog entries to the expected final destination. changelog.md is now just a pointer to the latest changelog + showing where to find instructions.
• so we're now writing current changelog entries to changelogs/changelog_1_4_0.md instead of changelog.md. Even if 1.4.0 ends up being something else (eg 2.0.0), the git
  history won't be destroyed because git will recognize this as a move, unlike what's been happening to changelogs before this PR because changelog.md keeps getting overwritten
• renamed changelogs/changelog_0_18_1.md => changelogs/changelog_0_18_0.md since that's what's on the website and 0.18.1 was not a release
• updated changelogs/readme.md with latest entries

note to reviewer

when merging, please "rebase and merge" instead of "squash and merge" so that, at least in git history, git will recognize changelogs/changelog_1_4_0.md as a move (as you can see with https://patch-diff.githubusercontent.com/raw/nim-lang/Nim/pull/14025.patch); git is not that smart about renames followed by re-introduction (with new content) of orginial file that was moved. It won't show as a move in github diff because of isaacs/github#900 but at least it will in git history)

[Clyybber]

This is IMO unneccessary complexity and makes backporting more cumbersome.

[timotheecour]

This is IMO unneccessary complexity and makes backporting more cumbersome.

not that's the exact opposite: less complexity and easier backport.
no files being moved around and renamed on each release, git history isn't destroyed, and if you backport a commit that changes a changelog entry, you'll get an easier to resolve merge conflict:

• deleted by us: changelogs/changelog_1_4_0.md
• instead of both modified: changelog.md

So with current approach which is to generate a final changelog for backported releases by aggregating commit messages, all you need is to git rm changelogs/changelog_1_4_0.md whenever such conflict occurs

[narimiran]

I've already begged you to slow down with your pull requests, so we don't have to play this ping-pong and burn both CI cycles and our time on reviewing the silly mistakes you make in a hurry.

Please, your time is not more valuable than others'.

---

Now, as for the content of this PR: I can see the benefits, but I can see some downsides too. I'm not convinced this is the way to go.

[timotheecour]

PTAL
https://github.com/timotheecour/Nim/blob/pr_fix_changelog_files/changelog.md now looks nice

[Araq]

@narimiran I'm in favour of the idea behind this change fwiw.

[krux02]

I do see the problem. Keeping old pull requests active causes really annoying problems each release when there are changelog entries. But I don't agree on the solution.

Why do you disrupt the workflow?
Why is there such a big diff?
Why don't you make changelog.md just a symlink?

[krux02]

Why did you rename changelogs/changelog_0_18_1.md → changelogs/changelog_0_18_0.md?

[krux02]

Why?

[krux02]

Why don't I see File renamed without changes. here?

[timotheecour]

this was explained in PR msg.
see https://patch-diff.githubusercontent.com/raw/nim-lang/Nim/pull/14025.patch

---
 changelog.md => changelogs/changelog_1_4_0.md |  0
 changelogs/changelog_X_XX_X.md                |  3 +--
 changelogs/readme.md                          | 27 +++++++++++++++----
 3 files changed, 23 insertions(+), 7 deletions(-)
 rename changelog.md => changelogs/changelog_1_4_0.md (100%)

[juancarlospaco]

I dont understand the diff, it should not be that big, old changelogs should be left untouched.
Symlinks wont work on all Windows AFAIK.

Alternatively you should steal the idea from https://github.com/juancarlospaco/changelogen#changelogen
Try it on your own fork, no merge conflicts on changelog.md all the time,
automatic links to diff per commit, arbitrary categories, JSON representation if needed, and other benefits.

[Araq]

Way too complex. Instead we could have changelog_1_3.md instead of changelog.md. A final rename step remains when we do the release.

[Araq]

Rejected for now, we should find a better way if still a problem after your .git config change.