[doc] Add changelog for v1.0.0rc1

CHANGELOG.md

+## [v1.0.0rc1](https://git.duniter.org/clients/python/duniterpy/-/milestones/12) (25th July 2021)
+**See below the main changes for the v1.0**
+
+### Fixes
+- #152, #170, !159: Fix `ESUserEndpoint` regex
+  - Fix datapod domain name in `request_data_elasticsearch` example
+
+### Development Environment
+- #149, !161: Change workflow by changing from `master` and default `dev` branches to a single `main` branch
+- Add changelog link to PyPI
+
+### Documentation
+- !160: Fix autodoc generation by running it into Poetry virtualenv
+- !158: Allow to trigger the documentation job without having the release stage completed
+
 ## [v1.0.0rc0](https://git.duniter.org/clients/python/duniterpy/-/milestones/12) (9th July 2021)
 
 TL;DR: The key changes are the `Documents` refactoring, the removal of the asynchronous property.