add capped characters validation for description

[manh-pendle]

PR Checklist

• My protocol folder name must be kebab-case.
• I have set all necessary fields like the example in README file.
• My protocol's icon is a png image and smaller than 20KB.
• I have set asset addresses correctly according to their types (PT token address for PT integrations, LP token address for LP integration, etc).
• I have set the integration URL valid and it points to the appropriate page.
• I did not change the global config.json file. This file will be automatically generated.