Add a changelog

Author: bbatsov

CHANGELOG.md

@@ -0,0 +1,7 @@
+# Change log
+
+## master (unreleased)
+
+## 1.0.0 (2020-09-15)
+
+Initial "stable" release after 9 years of development.

CONTRIBUTING.md

@@ -7,7 +7,7 @@ try to follow these guidelines when you do so.
 
 ## Issue reporting
 
-* Check that the [issue has not already been reported][5].
+* Check that the [issue has not already been reported][2].
 * Check that the issue has not already been fixed in the latest code
   (a.k.a. `master`).
 * Be clear, concise and precise in your description of the problem.
@@ -17,16 +17,18 @@ try to follow these guidelines when you do so.
 
 ## Pull requests
 
-* Read [how to properly contribute to open source projects on Github][2].
+* Read [how to properly contribute to open source projects on GitHub][3].
 * Use a topic branch to easily amend a pull request later, if necessary.
-* Write [good commit messages][3].
+* Write [good commit messages][4].
+* Update the [changelog][5].
 * Use the same coding conventions as the rest of the project.
 * Verify your Emacs Lisp code with `checkdoc` (<kbd>C-c ? d</kbd>).
-* Open a [pull request][4] that relates to *only* one subject with a clear title
+* Open a [pull request][6] that relates to *only* one subject with a clear title
   and description in grammatically correct, complete sentences.
 
 [1]: https://github.com/bbatsov/prelude/issues
-[2]: http://gun.io/blog/how-to-github-fork-branch-and-pull-request
-[3]: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
-[4]: https://help.github.com/articles/using-pull-requests
-[5]: https://github.com/bbatsov/prelude/issues?q=is:issue
+[2]: https://github.com/bbatsov/prelude/issues?q=is:issue
+[3]: http://gun.io/blog/how-to-github-fork-branch-and-pull-request
+[4]: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
+[5]: https://github.com/bbatsov/prelude/blob/master/CHANGELOG.md
+[6]: https://help.github.com/articles/using-pull-requests