[Modern] errors in documentation examples

in [/docs/pagination-container.html](https://facebook.github.io/relay/docs/pagination-container.html)

the example fails:
* ```@arguments``` is missing in the pagination query definition
* ```@argummentDefinitions``` is missing in the ```Feed_user``` fragment

in [/docs/mutations.html](https://facebook.github.io/relay/docs/mutations.html)
* ```deletedIDFieldName``` and ```connectionKeys.key``` should be quoted
* ```rangeBehavior ``` should not appear in ```RANGE_DELETE``` example since it is not used
* ```deletedIDFieldName```: the name of this parameter leads to confusion since
```deletedIDFieldName: 'removedId'```
is not similar to
```deletedIDFieldName: ['removedId']```
The documentation should draw our attention on this.
* ```connectionKeys```: The documentation does not state the updater will stop on the first connection found.