Improve side-aligned image positioning (#5876)

Co-authored-by: Hugo Locurcio <[email protected]>

_static/css/custom.css

@@ -217,6 +217,12 @@ legend,
     font-weight: 500;
 }
 
+/* See <https://github.com/godotengine/godot-docs/pull/5876> for context. */
+.rst-content .align-right,
+.rst-content .align-left {
+	clear: both;
+}
+
 .rst-content div.figure p.caption {
     /* Tweak caption styling to be closer to typical captions */
     text-align: center;