Update site tagline to RISC-V learnings and fun.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: hugomeiland

_includes/header.html

@@ -1,6 +1,6 @@
 <header class="page-header" role="banner">
     <h1 class="project-name">OpenSolvers</h1>
-    <h2 class="project-tagline">Running open solvers on RISC-V</h2>
+    <h2 class="project-tagline">RISC-V learnings and fun</h2>
 
     <a href="https://github.com/opensolvers/opensolvers.github.io" class="btn">Find us on GitHub</a>