Add missing img alt text.

src/LoginGate.tsx

@@ -56,7 +56,7 @@ class LoginGate extends React.Component {
           />
           <hr style={style.divider} />
           <ExternalLink style={style.isSafe} href="https://www.etesync.com/faq/#signed-pages">
-            <img src={SignedPagesBadge} />
+            <img alt="SignedPgaes badge" src={SignedPagesBadge} />
           </ExternalLink>
           <ul>
             <li><ExternalLink style={style.isSafe} href={C.homePage}>

src/SideMenu/index.tsx

@@ -76,7 +76,7 @@ class SideMenu extends React.PureComponent<PropsTypeInner> {
     return (
       <div style={{ overflowX: 'hidden', width: 250}}>
         <div className="App-drawer-header">
-          <img className="App-drawer-logo" src={logo} />
+          <img alt="App logo" className="App-drawer-logo" src={logo} />
           <div style={{ color: theme.palette.secondary.contrastText }} >
             {username}
           </div>