Remove spectral-cli (#5744) (#5751)

(cherry picked from commit 793cc87)

# Conflicts:
#	compiler-rs/clients_schema_to_openapi/package-lock.json
#	docs/examples/package-lock.json
#	docs/examples/package.json
#	package-lock.json
#	package.json

Author: pquentin

compiler-rs/clients_schema_to_openapi/README.md

@@ -20,7 +20,3 @@ flowchart LR
 This branch is the work for [PR #2047](https://github.com/elastic/elasticsearch-specification/pull/2047) where reviews and comments should be made.
 
 The OpenAPI specification generated from the current `schema.json` can be found in the [output/openapi](../../output/openapi) directory.
-
-The generated OpenAPI schemas validate successfully using the rather strict [Spectral OpenAPI linter](https://github.com/stoplightio/spectral), except for endpoint (this is an ES API issue). You can run the linter using:
-* `npm run validate` for the Stack/Stateful OpenAPI spec
-* `npm run validate-serverless` for the Serverless OpenAPI spec