Mention jed1.x format in documentation

[weekens]

Besides jed, po2json also accepts jed1.x format, which is not mentioned in documentation.

In fact, only after specifying jed1.x I was able to get my messages.js working with Jed v1.1.1.

The output of these two formats differs. In jed case, a leading null is inserted into a message specification array:

...
"Overload": [null, "Перегрузка"],
...

jed1.x:

...
"Overload": ["Перегрузка"],
...

The jed1.x format should definitely be mentioned in documentation.

[jhotadhari]

Hi,
had a similar problem.
Solution that works for me is using a newer version of po2json. And I still use jed as format.

npm i po2json --save-dev installed version 1.0.0-alpha

Output of npm ls po2json is:
├─┬ grunt-po2json@0.3.0
│ └── po2json@1.0.0-alpha deduped
└── po2json@1.0.0-alpha
So the newer version is now used by grunt-po2json