Add typing a container doc

[yleflour]

[bam-bot-tech]

	Fails
:no_entry_sign:	typing-a-container.s.md: You failed to mention a Bad Examples
:no_entry_sign:	typing-a-container.s.md: You failed to mention a Good Examples

	Warnings
:warning:	typing-a-container.s.md: Does not seem to be included in the root readme

Automatic reviewers

cc: @louiszawadzki, @tychota

Generated by :no_entry_sign: dangerJS