New article, content: error message should consist more information

When user creates too long article, there is error message:
"Content is too long"
There is no information about maximum length of article.

Test scenario
Pre-condition

1. User is logged in
2. Write article form is opened

Steps to reproduse

1. Fill Titlle field
2. Write Article text with length more than 65 000 charasters
3. Press "Create article" button

AR: "Content is too long"
ER: "Content is too long. It should be no longer then 65 000 characters"