site: add alt to images

components/upload/demo/avatar.md

@@ -73,7 +73,7 @@ class Avatar extends React.Component {
         beforeUpload={beforeUpload}
         onChange={this.handleChange}
       >
-        {imageUrl ? <img src={imageUrl} alt="" /> : uploadButton}
+        {imageUrl ? <img src={imageUrl} alt="avatar" /> : uploadButton}
       </Upload>
     );
   }

site/theme/template/Layout/Footer.jsx

@@ -226,7 +226,7 @@ class Footer extends React.Component {
             <Col md={6} sm={24} xs={24}>
               <div className="footer-center">
                 <h2>
-                  <img className="title-icon" src="https://gw.alipayobjects.com/zos/rmsportal/nBVXkrFdWHxbZlmMbsaH.svg" alt="" />
+                  <img className="title-icon" src="https://gw.alipayobjects.com/zos/rmsportal/nBVXkrFdWHxbZlmMbsaH.svg" alt="AFX Cloud" />
                   <FormattedMessage id="app.footer.more-product" />
                 </h2>
                 <div>