update readmes

ChatAvatarSetter/README.md

@@ -1,9 +1,44 @@
 # ChatAvatarSetter
 
-This bot will set the chat avatar based on the image sent to bot
+This Kotlin/JVM example changes a chat's avatar to the photo sent in that chat. It receives updates by long
+polling and demonstrates the Telegram Bot API [`setChatPhoto`](https://core.telegram.org/bots/api#setchatphoto)
+method with a multipart file upload.
+
+## Behavior
+
+- There is no command: every photo message received by the bot is a trigger.
+- The bot downloads the photo, uploads it as `sample.jpg`, and uses it as the avatar of the same chat.
+- After a successful update, it replies `Done`. If `setChatPhoto` fails, it logs the exception and replies
+  `Something went wrong (see logs)`.
+- Non-photo messages are ignored. In particular, an image sent as a document is not a photo message.
+
+The implementation does not restrict who may trigger it. In a group or supergroup, any member whose photo
+message reaches the bot can cause an avatar-change attempt.
+
+## Telegram setup and permissions
+
+1. Create a bot with [@BotFather](https://t.me/BotFather) and obtain its token.
+2. Add the bot to the group, supergroup, or channel whose avatar it should manage.
+3. Promote the bot to administrator and grant it the **Change chat info** permission
+   (`can_change_info`). It must also be able to send messages in a group or posts in a channel to deliver its
+   status reply.
+4. Send a photo directly in that chat.
+
+Telegram does not allow `setChatPhoto` to change private-chat photos. The target chat is always taken from the
+incoming photo message, so a photo sent to the bot privately cannot be used to update another chat.
+
+## Arguments
+
+| Position | Argument | Required | Description |
+| --- | --- | --- | --- |
+| 1 | `BOT_TOKEN` | Yes | Bot API token issued by BotFather. |
 
 ## Launch
 
+From the repository root, run:
+
 ```bash
-../gradlew run --args="BOT_TOKEN"
+./gradlew :ChatAvatarSetter:run --args="<BOT_TOKEN>"
 ```
+
+The process continues polling until it is stopped.