Change format of test/data-model-errors.json file (#758)

* Change format of test/data-model-errors.json file

Previously, this file was not valid JSON. Added braces
and updated README file accordingly.

* Change format of test/data-model-errors.json file

Previously, this file was not valid JSON. Replaced '['/']'
with '{'/'}'.
Also removed a trailing comma and corrected typo in README file.

Author: catamorphism

test/README.md

@@ -6,7 +6,7 @@ These test files are intended to be useful for testing multiple different messag
 - `syntax-errors.json` — An array of strings that should produce a Syntax Error when parsed.
 
 - `data-model-errors.json` - An object with string keys and arrays of strings as values,
-     where each key is the name of an error and its value is array of strings that
+     where each key is the name of an error and its value is an array of strings that
      should produce `error` when processed.
      Error names are defined in ["MessageFormat 2.0 Errors"](../spec/errors.md) in the spec.
 

test/data-model-errors.json

@@ -1,4 +1,4 @@
-[
+{
     "Variant Key Mismatch": [
         ".match {$foo :x} * * {{foo}}",
         ".match {$foo :x} {$bar :x} * {{foo}}"
@@ -23,10 +23,10 @@
         ".local $foo = {$bar} .local $bar = {$baz} {{_}}",
         ".local $foo = {$bar :func} .local $bar = {$baz} {{_}}",
         ".local $foo = {42 :func opt=$foo} {{_}}",
-        ".local $foo = {42 :func opt=$bar} .local $bar = {42} {{_}}",
+        ".local $foo = {42 :func opt=$bar} .local $bar = {42} {{_}}"
     ],
     "Duplicate Option Name": [
             "bad {:placeholder option=x option=x}",
             "bad {:placeholder ns:option=x ns:option=y}"
     ]
-]
+}