[GEN-1956]: add Groundcover inCloud destination support and documentation

[BenElferink]

This pull request includes several changes to add support for Groundcover as a new destination and to improve the documentation structure. The most important changes include adding Groundcover configuration, updating documentation to include Groundcover, and refactoring the documentation structure for better readability.

Groundcover Support:

• common/config/groundcover.go: Added Groundcover configuration, including endpoint and API key handling, and methods to modify the configuration.
• common/config/root.go: Included Groundcover in the list of available configurers.
• common/dests.go: Added Groundcover as a destination type.
• destinations/data/groundcover.yaml: Created a YAML file for Groundcover destination configuration.

Documentation Updates:

• docs/backends-overview.mdx: Added Groundcover to the list of managed destinations.
• docs/backends/groundcover.mdx: Created a new documentation file for configuring Groundcover inCloud.
• docs/mint.json: Refactored the documentation structure for better readability and included Groundcover in the list of backends. [1] [2] [3] [4] [5] [6] [7]
• docs/quickstart/next-steps.mdx: Added a card for Groundcover inCloud in the quickstart guide.

Minor Changes:

• README.md: Minor formatting adjustments for the key features and managed destinations sections. [1] [2] [3] [4]

[notion-workspace]

Destinations: add support for “groundcover”