docs: add License headers to website files and assets

[delei]

Purpose of the pull request

Closed: #840

What's changed?

• add License headers to website files(.md) and assets(.svg)
• bump license check action to v7
• update the licenserc.toml file

Result

Run this shell script

find website -type f \( -name "*.md" -o -name "*.svg" \) -exec grep -L "Licensed to the Apache Software Foundation" {} \;

not found

Checklist

• I have read the Contributor Guide.
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

[psxjoy]

LGTM