Some part way through the adding a language checklist.

lib/linguist/languages.yml

@@ -3135,6 +3135,24 @@ Smarty:
   ace_mode: smarty
   tm_scope: text.html.smarty
 
+SMT:
+  type: programming
+  extensions:
+  - .smt2
+  - .smt
+  interpreters:
+  - boolector
+  - cvc4
+  - mathsat5
+  - opensmt
+  - smtinterpol
+  - smt-rat
+  - stp
+  - verit
+  - yices2
+  - z3
+  tm_scope: source.smt
+
 SourcePawn:
   type: programming
   color: "#5c7611"