Use Vale Vocabularies

[colleenmcginnis]

Fixes #61

Adds two Vale Vocabularies containing Elastic product/feature names and third-party product names. This will likely be easier to manage exact product/feature names without having to add them as exceptions in individual styles.

Process

• I started with the list of exceptions in styles/Elastic/Capitalization.yml and sorted them into ElasticTerms (Elastic-specific products and features) vs. ThirdPartyProducts (non-Elastic products). I created two separate vocabulary files in case we ever want to sync this list of Elastic product names with others (like in docs-builder and the VS Code extension).
• Then I added all the product names from docs-builder's product list to ElasticTerms and deduplicated as needed.
• In ElasticTerms, for product and feature names that could also be used as a regular word (for example, Agent, Analytics, Machine Learning), I prefixed the strings with (?i) to mark the entire pattern as case-insensitive. This will allow us to use either the title case version when referring to the specific product/feature and the lower case version when using it as a regular word.
• Then I added a list of third-party products from a previous linting attempt to ThirdPartyProducts and deduplicated as needed.
• In ThirdPartyProducts, there are a several official product names that start with a lower case character. To account for when those product names are used at the beginning of the sentence, I prefixed the strings with (?i) to mark the entire pattern as case-insensitive. (This decision is definitely up for debate.)

Potential follow up tasks

• Update the contributing docs prompting contributors to add to these lists instead of individual style exceptions where appropriate.
• Consider adding an IndustryTerms list for additional items like GeoJSON and QoS.
• In the long term consider syncing Elastic product list names across tools (docs-builder, VS Code extension).

[theletterf]

This is excellent, thank you! I think the (?i) solution is brilliant as long as it doesn't interfere with rules where we want to preserve capitalization of proper nouns / product names in a certain way (which I think is not the case with the current PR). I'm merging this one :)

As for the next actions, I'm adding the recommendation about editing the Vocabulares in the PR I'm preparing for the public docs. For docs-builder integration, you might want to have a look at this one: elastic/docs-builder#1988