Added explanatory webhook text to UI. (#10782)

* Added explanatory webhook text to UI.

* Made new webhook API info translateable.

website/client/components/settings/api.vue

@@ -38,6 +38,7 @@
 
   .col-6
     h2 {{ $t('webhooks') }}
+    p(v-html="$t('webhooksInfo')")
     table.table.table-striped
       thead(v-if='user.webhooks.length')
         tr

website/common/locales/en/settings.json

@@ -157,6 +157,7 @@
     "generate": "Generate",
     "getCodes": "Get Codes",
     "webhooks": "Webhooks",
+    "webhooksInfo": "Habitica provides webhooks so that when certain actions occur in your account, information can be sent to a script on another website. You can specify those scripts here. Be careful with this feature because specifying an incorrect URL can cause errors or slowness in Habitica. For more information, see the wiki's <a target=\"_blank\" href=\"https://habitica.wikia.com/wiki/Webhooks\">Webhooks</a> page.",
     "enabled": "Enabled",
     "webhookURL": "Webhook URL",
     "invalidUrl": "invalid url",