Add/Remove & Fix loc strings

i18n/en.json

@@ -685,7 +685,7 @@
   },
   {
     "id": "api.post.check_for_out_of_channel_mentions.message.one",
-    "translation": "{{.Username}} was mentioned, but they do not belong to this channel."
+    "translation": "{{.Username}} was mentioned, but does not belong to this channel."
   },
   {
     "id": "api.post.create_post.bad_filename.error",

i18n/es.json

@@ -681,7 +681,7 @@
   },
   {
     "id": "api.post.check_for_out_of_channel_mentions.message.multiple",
-    "translation": "{{.Usernames}} y {{.LastUsername}} fueron mencionados, pero ellos no pertenecen a este canal."
+    "translation": "{{.Usernames}} y {{.LastUsername}} fueron mencionados, pero no pertenecen a este canal."
   },
   {
     "id": "api.post.check_for_out_of_channel_mentions.message.one",

web/static/i18n/es.json

@@ -933,6 +933,7 @@
   "signup_user_completed.gitlab": "con GitLab",
   "signup_user_completed.google": "con Google",
   "signup_user_completed.lets": "Vamos a crear tu cuenta",
+  "signup_user_completed.none": "No está habilitado ningún método para crear usuarios. Por favor contacta a un administrador para obtener acceso.",
   "signup_user_completed.onSite": "en {siteName}",
   "signup_user_completed.or": "o",
   "signup_user_completed.passwordLength": "Por favor ingresa al menos {min} caracteres",