Add Vale linter for style checking

[scott-klaytn]

Proposed changes

• Add Vale linter for automatic style checking to enforce consistent writing standards across all KIPs. It will run on every PR and provide suggestions, warnings and error based on pre-defined style rules
  • Google Developer Documentation Style Guide and Proslint style integrated
  • Kaia-specific rules added
    

Types of changes

Please put an x in the boxes related to your change.

• Bugfix
• KIP Proposal
• KIP Improvement

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• Used the suggested template: https://github.com/kaiachain/KIPs/blob/main/kip-template.md
• I have read the CLA and signed by comment I have read the CLA Document and I hereby sign the CLA in first time contribution
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

Related issues

Related to Kaia Docs PRs (#261, #266)

Further comments

[scott-klaytn]

I have read the CLA Document and I hereby sign the CLA