Chore: Add eslint-plugin-jsx-a11y (styleguidist#1138)

Part of styleguidist#879

Author: aghh1504

.eslintrc

@@ -1,13 +1,14 @@
 {
   "parser": "babel-eslint",
-  "extends": "tamia/react",
+  "extends": ["tamia/react", "plugin:jsx-a11y/recommended"],
   "env": {
     "browser": true,
     "node": true
   },
   "plugins": [
     "compat",
-    "import"
+    "import",
+    "jsx-a11y"
   ],
   "settings": {
     "import/resolver": {

examples/basic/src/components/Placeholder/Placeholder.js

@@ -47,6 +47,8 @@ export default class Placeholder extends Component {
 
 	render() {
 		const { width, height } = this.props;
-		return <img className="placeholder" src={this.getImageUrl()} width={width} height={height} />;
+		return (
+			<img className="placeholder" src={this.getImageUrl()} width={width} height={height} alt="" />
+		);
 	}
 }

examples/customised/src/components/Placeholder/Placeholder.js

@@ -47,6 +47,6 @@ export default class Placeholder extends Component {
 
 	render() {
 		const { width, height } = this.props;
-		return <img className={s.root} src={this.getImageUrl()} width={width} height={height} />;
+		return <img className={s.root} src={this.getImageUrl()} width={width} height={height} alt="" />;
 	}
 }

examples/preact/src/components/Placeholder/Placeholder.js

@@ -47,6 +47,8 @@ export default class Placeholder extends Component {
 
 	render() {
 		const { width, height } = this.props;
-		return <img className="placeholder" src={this.getImageUrl()} width={width} height={height} />;
+		return (
+			<img className="placeholder" src={this.getImageUrl()} width={width} height={height} alt="" />
+		);
 	}
 }

examples/sections/src/components/Placeholder/Placeholder.js

@@ -49,6 +49,8 @@ export default class Placeholder extends Component {
 
 	render() {
 		const { width, height } = this.props;
-		return <img className="placeholder" src={this.getImageUrl()} width={width} height={height} />;
+		return (
+			<img className="placeholder" src={this.getImageUrl()} width={width} height={height} alt="" />
+		);
 	}
 }