Update build-docs.yml

[ubukawa]

Reduced the update frequency of docs. (everyday to once a week)

Thank you for submitting a pull request!

Description

I modified github workflow to reduce the update frequency of docs. (everyday to once a week)
This is because our CLI is not updated yet.
(I edited only the frequency of cron job.)

Type of Pull Request

• Adding a feature
• Fixing a bug
• Maintaining documents
• [x ] Others ()

Verify the followings

• [x ] Code is up-to-date with the main branch
• [ n/a] No build errors after npm run build
• [ n/a] No lint errors after npm run lint
• [ n/a] No errors on using charites help globally
• [ n/a] Make sure all the existing features working well
• [ n/a] Have you added at least one unit test if you are going to add new feature?
• [ n/a] Have you updated documentation?

Refer to CONTRIBUTING.MD for more details.

[JinIgarashi]

@ubukawa created PR #157 instead

[ubukawa]

Thank you @JinIgarashi !