feat: upd mytonwallet switch testnet info (#726)

Co-authored-by: igor <i.verhusha@pixelplex.io>

docs/participate/wallets/apps.mdx

@@ -177,8 +177,12 @@ To switch OpenMask between Mainnet and Testnet: you need to click on "mainnet/te
 - ✅ Supports all major platforms (such as macOS, Linux and Windows) and also runs in Chrome as an extension.
 - ❌ Doesn't work in Firefox as an extension.
 
-#### MyTonWallet test environment
-To switch MyTonWallet to Testnet: open Settings and by clicking 5 times on the app version open the network switcher.
+#### MyTonWallet test environment (browser, desktop, and mobile application)
+
+1. Go to the Settings section.
+2. Scroll down and click on the MyTonWallet application version.
+3. In the pop-up window, select the environment.
+
 
 #### Links