Feature/api usage ui documentation

[brylie]

This pull request improves the usability for API backends by:

• Adding navigation link to API page from Catalogue view
• Displaying help text instructing user how to call API Umbrella

[brylie]

@apinf/developers please review ASAP, as this may be needed by the hackathon participants over the weekend. If this gets merged in time, it also needs to be deployed prior to the hackathon.

@ccsr please follow up.

[bajiat]

@mauriciovieira Can you review the PR? I understood that you have been discussing this with Brylie in IRC.
@elnzv If the code is ok and this is merged, would you be able to deploy it before tomorrow?

[brylie]

It is a quick usability fix for people to figure out how to work with a given API backend. The two main pages that have been modified are:

• API Catalogue now has links to individual API Backend pages
• API Backend page now has button (in upper right) that toggles a help box

There are sub-templates for the buttons and help box.

I also had to create a server method to get the API Umbrella base URL, since it is stored in a private setting.

Additional changes include a fix to the linter file.

[ccsr]

@mauriciovieira could you please review it and if everything is ok then please indicate to @elnzv so that he can go forward with the deployment

[mauriciovieira]

Sounds good! 👍