Add application sanitization information

[LoznianuAnamaria]

Let's add some information on our docs to inform our users that on the blockchain basically everything can be added. Whoever writes applications, needs to sanitize on their end the responses from our backend components.

This can be part of other tutorials and not a page in itself.

[jamiehewitt15]

Possibly we could create a page on security and this could be one of the sections

[LoznianuAnamaria]

This can be part of other tutorials and not a page in itself.

[LoznianuAnamaria]

Done in Docs V2