Update Vale guidelines checker and fix issues

[NicolasMassart]

Before pushing any commit in your pull request, make sure that:

• you read the contribution guidelines.
• all commits in this PR are signed off for the DCO.
• you have tested your changes locally before submitting them to the community for review.
• you verified the rendering on ReadTheDocs.org PR preview (see Testing)

Describe the change

• Update Vale to latest version https://github.com/errata-ai/vale/releases/tag/v2.6.6 (required to add all styles in the project as they are not included in Vale natively anymore)
• fixes the issues checked by styles
• add words in accepted list
• exclude Vale styles from markdown linting (not our docs)

Issue fixed

fixes #560

Impacted parts

For content changes

• Doc content
• Doc pages organisation

For tools changes

• CircleCI workflow
• Build and QA tools (lint, vale,…)
• MkDocs templates
• MkDocs configuration
• Python dependencies
• Node dependencies and JavaScript
• ReadTheDocs configuration
• Github integration

Review process

You can probably skip looking at the changes in CI/vale/vale_styles/Microsoft, CI/vale/vale_styles/proselint and CI/vale/vale_styles/write-good as they are imported styles I did not change them only moved them or added some.
Only the CI/vale/vale_styles/Besu and CI/vale/vale_styles/Vocab/Besu/accept.txt have changes that you should check.

Testing

Run CI/scripts/test_all.sh

[bgravenorst]

Minor suggestion.

[MadelineMurray]

Couple of minor comments. Nice to see all those spelling errors fixed :-)