Add formatting option for trailing comma

See redhat-developer/yaml-language-server#1063, this PR requires that
PR in order to work.

Fixes #1112

Signed-off-by: David Thompson <davthomp@redhat.com>

Author: datho7561

README.md

@@ -43,6 +43,7 @@ The following settings are supported:
 * `yaml.format.bracketSpacing`: Print spaces between brackets in objects
 * `yaml.format.proseWrap`: Always: wrap prose if it exceeds the print width, Never: never wrap the prose, Preserve: wrap prose as-is
 * `yaml.format.printWidth`: Specify the line length that the printer will wrap on
+* `yaml.format.trailingComma`: Specify if trailing commas should be used in JSON-like segments of the YAML
 * `yaml.validate`: Enable/disable validation feature
 * `yaml.hover`: Enable/disable hover
 * `yaml.completion`: Enable/disable autocompletion

package.json

@@ -148,6 +148,11 @@
           "default": 80,
           "description": "Specify the line length that the printer will wrap on"
         },
+        "yaml.format.trailingComma": {
+          "type": "boolean",
+          "default": true,
+          "description": "Specify if trailing commas should be used in JSON-like segments of the YAML"
+        },
         "yaml.validate": {
           "type": "boolean",
           "default": true,