update zh-cn/application-dev/security/cryptoFramework-guidelines.md.

Signed-off-by: N胡啸天 <huxiaotian2@huawei.com>

zh-cn/application-dev/security/cryptoFramework-guidelines.md

@@ -140,6 +140,8 @@ function convertAsyKey() {
 2. 调用convertKey方法，传入公钥二进制和私钥二进制（二者非必选项，可只传入其中一个），转换为KeyPair对象。
 
 ```js
+import cryptoFramework from '@ohos.security.cryptoFramework';
+
 function convertEccAsyKey() {
     let pubKeyArray = new Uint8Array([48,89,48,19,6,7,42,134,72,206,61,2,1,6,8,42,134,72,206,61,3,1,7,3,66,0,4,83,96,142,9,86,214,126,106,247,233,92,125,4,128,138,105,246,162,215,71,81,58,202,121,26,105,211,55,130,45,236,143,55,16,248,75,167,160,167,106,2,152,243,44,68,66,0,167,99,92,235,215,159,239,28,106,124,171,34,145,124,174,57,92]);
     let priKeyArray = new Uint8Array([48,49,2,1,1,4,32,115,56,137,35,207,0,60,191,90,61,136,105,210,16,27,4,171,57,10,61,123,40,189,28,34,207,236,22,45,223,10,189,160,10,6,8,42,134,72,206,61,3,1,7]);