feat: allow users to pass ring_color param (#2075)

* fix: prevent crash if undefined color is passed to func fallbackColor

* feat: allow users to pass ring_color param

Before this commit, the ring color was always equal to the title color.
This commit allows the user to pass a ring_color property to allow him
to style the ring color the way he pleases to. If no ring_color is
passed we default to the title color.

* docs: improves ring color documentation

* fix: improve code style

Co-authored-by: rickstaa <rick.staa@outlook.com>

tests/__snapshots__/renderWakatimeCard.test.js.snap

@@ -51,13 +51,13 @@ exports[`Test Render Wakatime Card should render correctly with compact layout 1
     }
 
     .rank-circle-rim {
-      stroke: #2f80ed;
+      stroke: undefined;
       fill: none;
       stroke-width: 6;
       opacity: 0.2;
     }
     .rank-circle {
-      stroke: #2f80ed;
+      stroke: undefined;
       stroke-dasharray: 250;
       fill: none;
       stroke-width: 6;