Added Olympic Rings at 678 bytes (#580)

* resized and adapted olympic rings from wikipedia

* added olympics.svg entry to the README

* added olympic rings reference

images/svg/olympics.svg

@@ -0,0 +1,14 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+aria-label="Olympic Rings" role="img"
+viewBox="0 0 512 512"><rect
+width="512" height="512"
+rx="15%"
+fill="#fff"/><g stroke-width="11.4" stroke="#000" fill="none"><circle
+cx="115.6" cy="226" r="59.1" stroke="#0081c8"/><circle
+cx="256" cy="226" r="59.1"/><circle
+cx="396.4" cy="226" r="59.1" stroke="#ee334e"/><circle
+cx="185.8" cy="286" r="59.1" stroke="#fcb131"/><circle
+cx="326.2" cy="286" r="59.1" stroke="#00a651"/><path
+d="m162.9 190.5a59.1 59.1 90 010 70.9" stroke="#0081c8"/><path
+d="m303.3 190.5a59.1 59.1 90 010 71M256 285.1a59.1 59.1 90 01-35.5-11.8"/><path
+d="m396.4 285.1a59.1 59.1 90 01-35.5-11.8" stroke="#ee334e"/></g></svg>