[enh] update README.md and CHANGELOG.md

CHANGELOG.md

+## v0.53.2 (18/01/2021)
+
+This is the last version released by Vit.
+No more new version or maintenance will be done.
+Thanks to Inso for this wonderful project, and to every enthusiast users.
+
+### Bugs
+* #809 fix About Sakia available release search code and obsolete link to Github in exception
+* #813 remove obsolete github references in README.md
+* #815 remove unused dependency asynctest from requirements.txt
+* fix "make tests" command running test scripts from AppDir in ci/appimage
+
 ## v0.53.1 (1/11/2020)
 ### Bugs
 * #811 Fix WoT window is blank when clicking Explore until the menu "Show in WoT" is used.

README.md

 ![sakia logo](https://git.duniter.org/clients/python/sakia/-/raw/master/sakia.png)
 
+This project is not maintained anymore since 18/01/2021.
+No more new version or maintenance will be done.
+
+Vit thanks Inso for this wonderful project, and every enthusiast users.
+
 # Sakia
  [![coverage report](https://git.duniter.org/clients/python/sakia/badges/gitlab/coverage.svg)](https://git.duniter.org/clients/python/sakia/commits/gitlab)
  [![pipeline status](https://git.duniter.org/clients/python/sakia/badges/gitlab/pipeline.svg)](https://git.duniter.org/clients/python/sakia/commits/gitlab)