assets: remove qq and wechat group

.gitignore

@@ -42,5 +42,4 @@ website/src/modern-cpp/exercises
 website/src/modern-cpp/code
 website/src/modern-cpp/assets/cover-2nd-en.png
 website/src/modern-cpp/assets/cover-2nd.png
-website/src/modern-cpp/assets/qq-group.png
 website/src/modern-cpp/assets/figures/*

assets/community.md

@@ -9,17 +9,3 @@ order: 2
 The book offers a telegram chat group, feel free to join if you are interested:
 
 [![](https://img.shields.io/badge/chat-telegram-blue.svg?style=popout-square&logo=telegram)](https://t.me/joinchat/FEeulBM5OVYzuDI4phQ9Mg)
-
-## 交流
-
-本书有以下读者 QQ 交流群，有兴趣的读者可以加入，加群需正确回答加群密码：
-
-![](../assets/qq-group.png)
-
-> 提示: `bW9kZXJuLWNwcC10dXRvcmlhbC1naXRodWI=`
-
-本书还提供以下读者微信交流群，有兴趣的读者可以加入，加群请扫描如下二维码：
-
-![](../assets/wechat-group.jpg)
-
-若群已加满，请联系并添加 `oulongqi` 并注明『现代 C++ 教程』获取入群邀请。

website/Makefile

@@ -5,8 +5,6 @@ all: clean
 	cp ../assets/cover-2nd-en.png ./src/modern-cpp/assets/cover-2nd-en.png
 	cp ../assets/alipay.jpg ./src/modern-cpp/assets/alipay.jpg
 	cp ../assets/wechat.jpg ./src/modern-cpp/assets/wechat.jpg
-	cp ../assets/wechat-group.jpg ./src/modern-cpp/assets/wechat-group.jpg
-	cp ../assets/qq-group.png ./src/modern-cpp/assets/qq-group.png
 	cp ../assets/donate.md ./src/modern-cpp/about/
 	cp ../assets/community.md ./src/modern-cpp/about/
 	cp -r ../assets/figures ./src/modern-cpp/assets/figures
@@ -21,7 +19,6 @@ clean:
 		./src/modern-cpp/assets/figures \
 		./src/modern-cpp/assets/alipay.jpg \
 		./src/modern-cpp/assets/wechat.jpg \
-		./src/modern-cpp/assets/wechat-group.jpg \
 		./src/modern-cpp/about/donate.md \
 		./src/modern-cpp/about/community.md \
 		./src/modern-cpp/code \