Add missing semicolon in docs (egraphs-good#117)

Author: lyxell

src/tutorials/_02_getting_started.rs

@@ -127,7 +127,7 @@ egraph.rebuild();
 
 // now we can find a match since a = b
 let matches = pat.search(&egraph);
-assert!(!matches.is_empty())
+assert!(!matches.is_empty());
 ```