Add TypeScript terms to the cSpell dictionary

v6-dev now spell-checks .ts files. Add the technical terms the migration
introduced: desync, disableable, extensionless, unnamespaced.

Author: mdo

.cspell.json

@@ -51,7 +51,9 @@
     "Datepicker",
     "Deque",
     "describedby",
+    "desync",
     "dialogbase",
+    "disableable",
     "discoverability",
     "docsref",
     "DOMCONTENT",
@@ -62,6 +64,7 @@
     "dgst",
     "errorf",
     "esproj",
+    "extensionless",
     "favicon",
     "favicons",
     "fieldsets",
@@ -178,6 +181,7 @@
     "touchend",
     "twbs",
     "unitless",
+    "unnamespaced",
     "Unported",
     "unstylable",
     "unstyled",