doc: add donation badge and link with crypto payment (#1457)

README.md

@@ -15,6 +15,8 @@
 [![][badge-discord]][link-discord]
 [![AGPL Licence][badge-license]](LICENSE)
 [![Latest release][badge-release]][link-gh-releases]
+[![Donate][badge-donate]][link-donate]
+<br>
 [![Last commit][badge-last-commit]][link-gh-commits]
 [![Commits][badge-commit-activity]][link-gh-pulse]
 
@@ -277,6 +279,8 @@ The following fonts are utilized in this software, either bundled within the app
 [badge-commit-activity]: https://img.shields.io/github/commit-activity/m/readest/readest
 [badge-discord]: https://img.shields.io/discord/1314226120886976544?color=5865F2&label=discord&labelColor=black&logo=discord&logoColor=white&style=flat-square
 [badge-hellogithub]: https://abroad.hellogithub.com/v1/widgets/recommend.svg?rid=8a5b6ade2aee461a8bd94e59200682a7&claim_uid=eRLUbPOy2qZtDgw&theme=small
+[badge-donate]: https://donate.readest.com/badge.svg
+[link-donate]: https://donate.readest.com/?tickers=btc%2Ceth%2Csol%2Cusdc
 [link-appstore]: https://apps.apple.com/app/apple-store/id6738622779?pt=127463130&ct=github&mt=8
 [link-website]: https://readest.com?utm_source=github&utm_medium=referral&utm_campaign=readme
 [link-web-readest]: https://web.readest.com