docs: add tag infos to readme files

[MikeMcC399]

Issue

The README files deal inconsistently with information about which tags are used by Cypress Docker images:

• README
• factory/README
• base/README
• browsers/README
• included/README

Background

Tags are created through factory/docker-compose.yml.

cypress-docker-images/factory/docker-compose.yml

Lines 15 to 16 in 55c80b6

	- ${REPO_PREFIX-}cypress/factory:latest
	- ${REPO_PREFIX-}cypress/factory:${FACTORY_VERSION}

cypress-docker-images/factory/docker-compose.yml

Lines 66 to 67 in 55c80b6

	- ${REPO_PREFIX-}cypress/base:latest
	- ${REPO_PREFIX-}cypress/base:${BASE_IMAGE_TAG}

cypress-docker-images/factory/docker-compose.yml

Lines 52 to 53 in 55c80b6

	- ${REPO_PREFIX-}cypress/browsers:latest
	- ${REPO_PREFIX-}cypress/browsers:${BROWSERS_IMAGE_TAG}

cypress-docker-images/factory/docker-compose.yml

Lines 34 to 36 in 55c80b6

	- ${REPO_PREFIX-}cypress/included:latest
	- ${REPO_PREFIX-}cypress/included:${INCLUDED_IMAGE_SHORT_TAG}
	- ${REPO_PREFIX-}cypress/included:${INCLUDED_IMAGE_TAG}

in combination with

cypress-docker-images/factory/.env

Lines 40 to 46 in 55c80b6

	# Tags used for the docker images generated from the factory. Keep in mind the docker images will only release if these versions change.
	BASE_IMAGE_TAG="${NODE_VERSION}"
	BROWSERS_IMAGE_TAG="node-${NODE_VERSION}-chrome-${CHROME_VERSION}-ff-${FIREFOX_VERSION}-edge-${EDGE_VERSION}"
	INCLUDED_IMAGE_SHORT_TAG="${CYPRESS_VERSION}"
	INCLUDED_IMAGE_TAG="cypress-${CYPRESS_VERSION}-${BROWSERS_IMAGE_TAG}"

Changes

• The example versions used in the README are refreshed.

• The information described in the Background section above is extracted and added to the respective README files.

[cypress-app-bot]

• Create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.

[jennifer-shehane]

This looks great. Thanks!