Some rewording & reformatting of the 'mission', and extending the 'development/getting started' page.
Initial draft of a mission statement for Flamenco project based on original blog post announcing Flamenco v3. Based on contribution suggestion from https://blender.chat/channel/flamenco?msg=uQq4thF8uBu7X5FQq Reviewed-on: https://projects.blender.org/studio/flamenco/pulls/104207