"Manage dependencies" should be a separate chapter

[bartlomieju]

https://deno.land/[email protected]/examples/manage_dependencies

Currently this chapter is very short and not in-depth, whilst the subject at hand is huge.

We should have a separate chapter for how to manage dependencies, including:

• examples of existing community tools
• anti-patterns
• how it's different than Node dep management
• how it's similar to Node dep management

[kt3k]

We should mention udd.

Also there is an automated bot https://github.com/hasundue/denopendabot

[kwhinnery]

keeping for now - docs coverage of dependency management could be improved for sure

[thisisjofrank]

We now have a separate managing dependencies page