Add this to docState context. (vuejs#975)

* Add french translation link

Signed-off-by: Bruno Lesieur <bruno.lesieur@gmail.com>

* kebab-case explaination updates

Signed-off-by: Bruno Lesieur <bruno.lesieur@gmail.com>

* kebab-case to kebab-cased

Signed-off-by: Bruno Lesieur <bruno.lesieur@gmail.com>

* Remove space before self-closing component

* Add this before docState in JavaScript version.

Signed-off-by: Bruno Lesieur <bruno.lesieur@gmail.com>

Author: MachinisteWeb

src/v2/guide/transitions.md

@@ -651,7 +651,7 @@ Which could also be written as:
 // ...
 computed: {
   buttonMessage: function () {
-    switch (docState) {
+    switch (this.docState) {
       case 'saved': return 'Edit'
       case 'edited': return 'Save'
       case 'editing': return 'Cancel'