Add initial documentation for Button component

src/cryptometrics/components/button/Button.js

-import classNames from "classnames";
 import React from "react";
+import PropTypes from "prop-types";
+import classNames from "classnames";
 
-export default function Button({ children, className, onClick }) {
+/**
+ * Custom button component
+ *
+ * @component
+ * @example
+ * return (
+ *   <Button className="bg-indigo-500 text-white" onClick={() => console.log("Button pressed")}>
+ *      Hello!
+ *   </Button>
+ * )
+ */
+function Button({ children, className, onClick }) {
   return (
     <button
       className={classNames("py-2 px-5 rounded-xl", className)}
@@ -11,3 +23,20 @@ export default function Button({ children, className, onClick }) {
     </button>
   );
 }
+
+Button.propTypes = {
+  /**
+   * The content inside the button
+   */
+  children: PropTypes.node.isRequired,
+  /**
+   * Additional CSS classes for the button (optional)
+   */
+  className: PropTypes.string,
+  /**
+   * The function to run when button is pressed
+   */
+  onClick: PropTypes.func,
+};
+
+export default Button;