Enhance usage instructions for API

[bajiat]

In the View API backend page, there is a "View usage instructions" button. Pressing the button opens the following instructions:

"Make API calls to:
[automatically filled request URL]

Note: you may need to use your API Key, found on your profile page."

Based on feedback through the APIKA support channel, there is a need to enhance these instructions.

Optimally, the instructions should include the parameter of using API key (api_key) in the request coupled with the user's actual API key.
As a minimum, the instruction could include how to use API key in request (i.e. the parameter api_key).

Refer also to bug report #606.

[saralavanip]

Verified on latest develop version.
Still have issue while calling API. Usage instructions could be more explanatory, providing URL that includes user API key.

Reported bugs:
https://github.com/apinf/api-umbrella-dashboard/issues/606
https://github.com/apinf/api-umbrella-dashboard/issues/758

[bajiat]

@frenchbread Will you take this task? Brylie can give you some guidance, if needed.

[frenchbread]

@bajiat Self-assigned

[frenchbread]

PR #801.
Looks like: