fix(audit-level): add info audit level

This is a valid level but wasn't configured to be allowed.

Also added this param to the usage output for `npm audit`

PR-URL: #2923
Credit: @wraithgar
Close: #2923
Reviewed-by: @ruyadorno

lib/audit.js

@@ -18,6 +18,7 @@ class Audit extends BaseCommand {
   /* istanbul ignore next - see test/lib/load-all-commands.js */
   static get params () {
     return [
+      'audit-level',
       'dry-run',
       'force',
       'json',

lib/utils/config/definitions.js

@@ -220,7 +220,7 @@ define('audit', {
 
 define('audit-level', {
   default: null,
-  type: ['low', 'moderate', 'high', 'critical', 'none', null],
+  type: ['info', 'low', 'moderate', 'high', 'critical', 'none', null],
   description: `
     The minimum level of vulnerability for \`npm audit\` to exit with
     a non-zero exit code.

tap-snapshots/test-lib-utils-config-describe-all.js-TAP.test.js

@@ -64,7 +64,7 @@ registry and all registries configured for scopes. See the documentation for
 #### \`audit-level\`
 
 * Default: null
-* Type: "low", "moderate", "high", "critical", "none", or null
+* Type: "info", "low", "moderate", "high", "critical", "none", or null
 
 The minimum level of vulnerability for \`npm audit\` to exit with a non-zero
 exit code.

tap-snapshots/test-lib-utils-npm-usage.js-TAP.test.js

@@ -204,7 +204,7 @@ All commands:
                     npm audit [fix]
                     
                     Options:
-                    [--dry-run] [-f|--force] [--json] [--package-lock-only] [--production]
+                    [--audit-level <info|low|moderate|high|critical|none>] [--dry-run] [-f|--force] [--json] [--package-lock-only] [--production]
                     
                     Run "npm help audit" for more info