Provide docker documentation

[anderspeders]

A host government / country site host will have the following options for costumization:

• Select front page image
• Select colors for site
• Editable pages (at buttom of screen)
• Translation (eg. Tunisia would need French / English)

@charlesyoung any other custom requests from country site hosts should be added here for consideration?

@anjesh to assign staff at YI to implement

[sadhakbj]

We already have following options available for country site customization:

• Selecting front page image (by logging in )
• Editable pages

Similarly the color can be selecting during the docker installation. (By providing the color code for primary and secondary colors - for now)