Add examples in multiple languages

[svenvNL]

Fission supports a lot of languages, but the documentation has examples in a single language. The introduction to writing a function has an example in JavaScript, while the section about configmaps has an example in Python.

I would propose to have examples in all the available languages. Google Developer Documentation has a great example with Firebase Cloud Firestore. Functions and Fission are new concepts for lots of developers, having documentation with in the language they are familiar with, makes it a bit easier to get started with Fission.

Templates already have support for it. It is for example used on the installation guide page.