[doc] readme: Update clients links

Add tikka repository link
sakia domain name have been freed
Point to repository

README.md

 # DuniterPy
 Most complete client oriented Python library for [Duniter](https://git.duniter.org/nodes/typescript/duniter)/Ğ1 ecosystem.
 
-This library was originally developed for [Sakia](http://sakia-wallet.org/) desktop client which is now discontinued.
+This library was originally developed for [Sakia](https://git.duniter.org/clients/python/sakia) desktop client which is now discontinued.
 It is currently used by following programs:
-- [Tikka](https://git.duniter.org/clients/python), the desktop client (Work In Progress, not yet available).
+- [Tikka](https://git.duniter.org/clients/python/tikka), the desktop client.
 - [Silkaj](https://silkaj.duniter.org/), command line client.
 - [Jaklis](https://git.p2p.legal/axiom-team/jaklis), command line client for Cs+/Gchange pods.
 - [Ğ1Dons](https://git.duniter.org/matograine/g1pourboire), Ğ1Dons, paper-wallet generator aimed at giving tips in Ğ1.