Implement Vale as linter

[BoHristova]

What would you like to be added:
The documentation repo needs a linter. A good solution would be to introduce Vale, which is a style editor with an integrated spelling checker.

Definition of Done:

• Initial set of Vale rules (based on the current style guide) and vocabularies
• make targets
• CI linting check
• PR review - either via Vale Linter or Coderabbit