Restore standard "si" binding for cider-jack-in-clj

It appears that this is still the common binding across all +lang layers.

CHANGELOG.develop

@@ -1219,6 +1219,8 @@ Other:
   - ~SPC m g g~ changed to =spacemacs/clj-find-var=, a wrapper for
     =cider-find-var= if REPL running, otherwise =dumb-jump-go=
     (thanks to John Stevenson)
+  - Restore standard =SPC m s i= binding for =cider-jack-in-clj=
+    (thanks to Russell Mull)
 - Fixes:
   - Remove `cider.nrepl/cider-middleware` in lein quick start setting
   - Fixed =cider-inspector-prev-page= binding, also add ~p~ as another key

layers/+lang/clojure/packages.el

@@ -118,6 +118,7 @@
             "sE" 'spacemacs/cider-send-last-sexp-to-repl-focus
             "sf" 'spacemacs/cider-send-function-to-repl
             "sF" 'spacemacs/cider-send-function-to-repl-focus
+            "si" 'cider-jack-in-clj
             "sjc" 'cider-jack-in-clj
             "sjf" 'cider-jack-in-clj&cljs
             "sjs" 'cider-jack-in-cljs