Add dependencies to manifest documentation. Add namespace to last versioned docs.

[seanson]

Resolves #420
This adds documentation to the extended notation for dependencies in the Okteto manifest.

The contributing docs mentions that only current documentation should be modified but I am not sure how that works with documentation changes that are both present in previous versions and about to change with the 3.x release, so I have added an extra change to the 1.24 version documentation.

If this is not ideal then I'm glad to amend the commit.

[pchico83]

Let's remove this line. That way everything is index under dependencies

[seanson]

Is there a good way we can communicate that this property has a simple and an extended notation then? I like the idea of the formatting being consistent but need a way as a consumer to know that there are two explicit versions. (Sidenote, is there a YAML schema for the Okteto file somewhere?)

[pchico83]

We don't have a YAML schema for the Okteto Manifest yet 😥
Are you familiar with any documentation where they document different field types?
I have been looking for inspiration, but didn't find anything great

[pchico83]

I would use the same format that we use in the build section. We put the sample first, and then a list of items explaining each field

[pchico83]

Thanks @seanson for taking care of this! I suggested using the same format as similar sections, but I am happy to consider a different formatting if you find it more practical