Add example client links

Add Thunderbird Android and K-9 mail for client details

Author: AdityaGarg8

README.md

@@ -72,7 +72,7 @@ It will notify you if this is the case.
 As part of the proxy setup process you need to provide an OAuth 2.0 `client_id` and (in many cases) a `client_secret` to allow it to authenticate with email servers on your behalf.
 
 If you have an existing client ID and secret for a desktop app, you can use these directly in the proxy.
-If this is not possible, you can also reuse the client ID and secret from any email client that supports IMAP/POP/SMTP OAuth 2.0 authentication with the email server you would like to connect to (such as [the](https://github.com/mozilla/releases-comm-central/blob/812b7c9068ca5cac0580b0ddbea8e34c141cd441/mailnews/base/src/OAuth2Providers.jsm) [many](https://github.com/mozilla/releases-comm-central/blob/master/mailnews/base/src/OAuth2Providers.sys.mjs) [existing](https://github.com/Foundry376/Mailspring/blob/master/app/internal_packages/onboarding/lib/onboarding-constants.ts) [open](https://gitlab.gnome.org/GNOME/evolution-data-server/-/blob/master/CMakeLists.txt) [source](https://gitlab.gnome.org/GNOME/gnome-online-accounts/-/blob/master/meson_options.txt) [clients](https://github.com/M66B/FairEmail/blob/master/app/src/main/res/xml/providers.xml) with OAuth 2.0 support), but please do this with care and restraint as access through reused tokens will be associated with the token owner rather than your own client.
+If this is not possible, you can also reuse the client ID and secret from any email client that supports IMAP/POP/SMTP OAuth 2.0 authentication with the email server you would like to connect to (such as [the](https://github.com/mozilla/releases-comm-central/blob/master/mailnews/base/src/OAuth2Providers.sys.mjs) [many](https://github.com/Foundry376/Mailspring/blob/master/app/internal_packages/onboarding/lib/onboarding-constants.ts) [existing](https://gitlab.gnome.org/GNOME/evolution-data-server/-/blob/master/CMakeLists.txt) [open](https://gitlab.gnome.org/GNOME/gnome-online-accounts/-/blob/master/meson_options.txt) [source](https://github.com/M66B/FairEmail/blob/master/app/src/main/res/xml/providers.xml) [clients](https://github.com/thunderbird/thunderbird-android/blob/main/app-thunderbird/src/release/kotlin/net/thunderbird/android/auth/TbOAuthConfigurationFactory.kt) [with](https://github.com/thunderbird/thunderbird-android/blob/main/app-k9mail/src/release/kotlin/app/k9mail/auth/K9OAuthConfigurationFactory.kt) OAuth 2.0 support), but please do this with care and restraint as access through reused tokens will be associated with the token owner rather than your own client.
 
 If you do not want to use credentials from an existing client you will need to register your own.
 The process to do this is different for each provider, but the registration guides for several common ones are linked here.