📄🔧：ensure no gap btwx stab-index banner & hero

The gap (unneeded) is more visible/intolerable on mobile.

Should be kept in mind when designing stability banner assets.

Signed-off-by: Derek Lewis <dereknongeneric@open.inf.is>

README.md

@@ -1,8 +1,7 @@
 <div align="center">
 
-[!['Tesselation of swarm of cicadas flying into school of fish and translating into flying doves'][main-readme-hero]][main-readme-hero-url]
-<br />
-[![Orange banner indicating a preview software component][release-level-banner--unstable]](##)
+<!-- markdownlint-disable-next-line line-length -->
+[!['Tesselation of swarm of cicadas flying into school of fish and translating into flying doves'][main-readme-hero]][main-readme-hero-url][![Orange banner indicating a preview software component][release-level-banner--unstable]](##)
 
 </div>