Update Positioning

[DanieldeR]

The current version of the documentation is lacking in its description of:

• positioning
• who the product is for or why they would use it
• how is Cartographer differentiated from other products in the K8s CI/CD space

The intent of this issue is to update the docs to clarify each of the above items. The update that are necessary apply to both the docs and to the landing page of Cartographer.

[emmjohnson]

@rawlingsj do you have any updates here?

[squeedee]

Include Single vendor discussion?