Bad link to the `cobra-cli` README.md

[a-poor]

The following link in the "Getting Started" page is bad:

cobra.dev/content/home/getting-started.md

Line 39 in 12b631a

[Here](https://github.com/spf13/cobra/blob/master/cobra/README.md) you can find more information about it.

I'm proposing changing this to the main README from the cobra-cli's separate repo: https://github.com/spf13/cobra-cli/blob/main/README.md

I'm happy to create a PR to make the change. Thanks!

[a-poor]

Sorry, looks like this is already covered by #4 and fixed in #5

[SebTM]

There are three solutions now for the broken link, I was about to PR a fourth as I encounter the problem every-time I use the page - maybe we can resolve this by merging #5 which looks the most comprehensive solution.