Added an option to display a custom footer

Added an option in config file.
Added a component which renders the custom footer or a default footer if
no custom footer is defined.
Updated readme file with related instructions.

src/components/footer/index.jsx

@@ -0,0 +1,41 @@
+import PropTypes from 'prop-types';
+
+import { skeleton } from '../../helpers/utils';
+
+const DefaultFooter = () => {
+  return (
+    <a
+      href="https://github.com/arifszn/gitprofile"
+      target="_blank"
+      rel="noreferrer"
+    >
+      <div>
+        <p className="font-mono text-sm">
+          Made with <span className="text-primary">GitProfile</span> and ❤️
+        </p>
+      </div>
+    </a>
+  );
+};
+
+const Footer = ({ content, loading }) => {
+  let footerContent = null;
+  if (content) {
+    footerContent = <div dangerouslySetInnerHTML={{ __html: content }} />;
+  } else {
+    footerContent = <DefaultFooter />;
+  }
+
+  return (
+    <div className="card-body">
+      {loading ? skeleton({ width: 'w-52', height: 'h-6' }) : footerContent}
+    </div>
+  );
+};
+
+Footer.propTypes = {
+  content: PropTypes.string,
+  loading: PropTypes.bool.isRequired,
+};
+
+export default Footer;