ci: add cspell.json to filetypes dictionary (streetsidesoftware#459)

Author: Jason3S

dictionaries/filetypes/cspell.json

@@ -0,0 +1,12 @@
+{
+    "files": [
+        "**/*.{md,txt}"
+    ],
+    "dictionaries": [
+        "filetypes"
+    ],
+    "import": [
+        "./cspell-ext.json"
+    ],
+    "ignoreWords": []
+}