add donation buttons

Author: Christophe Delord

.github/FUNDING.yml

@@ -1 +1,3 @@
 github: CDSoft
+liberapay: LuaX
+ko_fi: CDSoft

README.md

@@ -50,8 +50,9 @@ invited to contribute financially to its development.
 
 These prices are per month and per tools (see [`PRICING`](PRICING)).
 
-- donate with Liberapay: <https://liberapay.com/LuaX/donate>
-- donate with GitHub Sponsor: <https://github.com/sponsors/CDSoft>
+<a href='https://liberapay.com/LuaX/donate' target='_blank'><img height='36' style='border:0px;height:36px;' src='https://liberapay.com/assets/widgets/donate.svg' border='0' alt='Donate using Liberapay' /></a>
+<a href='https://ko-fi.com/K3K11CD108' target='_blank'><img height='36' style='border:0px;height:36px;' src='https://storage.ko-fi.com/cdn/kofi6.png?v=6' border='0' alt='Buy Me a Coffee at ko-fi.com' /></a>
+<a href='https://github.com/sponsors/CDSoft' target='_blank'><img height='36' style='border:0px;height:36px;' src='https://img.shields.io/static/v1?label=Sponsor&message=%E2%9D%A4&logo=GitHub&color=%23fe8e86' border='0' alt='Donate using Github' /></a>
 
 Feel free to promote Ypp!
 

doc/ypp.md

@@ -58,8 +58,13 @@ users are cordially invited to contribute financially to its development.
 
 These prices are per month and per tools (see [`PRICING`](PRICING)).
 
-- donate with Liberapay: <https://liberapay.com/LuaX/donate>
-- donate with GitHub Sponsor: <https://github.com/sponsors/CDSoft>
+@@[[ donate = function(url) return function(img) return function(alt)
+    return ("<a href='%s' target='_blank'><img height='36' style='border:0px;height:36px;' src='%s' border='0' alt='%s' /></a>"):format(url, img, alt)
+end end end]]
+
+@donate "https://liberapay.com/LuaX/donate"  "https://liberapay.com/assets/widgets/donate.svg"                                              "Donate using Liberapay"
+@donate "https://ko-fi.com/K3K11CD108"       "https://storage.ko-fi.com/cdn/kofi6.png?v=6"                                                  "Buy Me a Coffee at ko-fi.com"
+@donate "https://github.com/sponsors/CDSoft" "https://img.shields.io/static/v1?label=Sponsor&message=%E2%9D%A4&logo=GitHub&color=%23fe8e86" "Donate using Github"
 
 Feel free to promote Ypp!