update description for book/02 (#722)

* add some description for book/02 * Update README.cn.md * Update README.cn.md * update reademe * update

update description for book/02 (#722)
* add some description for book/02 * Update README.cn.md * Update README.cn.md * update reademe * update
693496f2 · xiaoting · Cheerego · 2cb2a522 · 693496f2 · 693496f2
7 changed file
--- a/02.recognize_digits/README.cn.md
+++ b/02.recognize_digits/README.cn.md
--- a/02.recognize_digits/image/01.png
+++ b/02.recognize_digits/image/01.png
--- a/02.recognize_digits/image/02.png
+++ b/02.recognize_digits/image/02.png
--- a/02.recognize_digits/image/03.png
+++ b/02.recognize_digits/image/03.png
--- a/02.recognize_digits/image/04.png
+++ b/02.recognize_digits/image/04.png
--- a/02.recognize_digits/image/05.png
+++ b/02.recognize_digits/image/05.png
--- a/02.recognize_digits/index.cn.html
+++ b/02.recognize_digits/index.cn.html