Replace "Proposal" with "Session" in nav bar

Author: axelboc

Diff for: ui/src/components/MXNavbar/MXNavbar.jsx

@@ -95,7 +95,7 @@ function MXNavbar() {
                 }}
               >
                 <span className="me-2 fas fa-lg fa-bars" />
-                Proposal
+                Session
                 <span className={styles.parens}> ({selectedProposal})</span>
               </button>
             )}