Add missing documentation examples for BinaryHeap.

[nathankleyn]

As part of the ongoing effort to document all methods with examples,
this commit adds the missing examples for the BinaryHeap collection
type.

This is part of issue #29348.

r? @steveklabnik

[steveklabnik]

same comment about basic usage from the other PR here

[nathankleyn]

Fixed!

[steveklabnik]

@bors: r+ rollup

Thanks so much!

[bors]

📌 Commit 04436fb has been approved by steveklabnik

[steveklabnik]

@bors: r-

the travis failure here is legit, there's an extra mut.

[nathankleyn]

@steveklabnik Fixed!

On a related note, what is your workflow for running these tests quickly and easily as you make doc changes? Now that I'm trying to get more involved and doing more, I'd really like to understand a bit more about how you work on a day-to-day basis, especially so I can avoid silly mistakes like this! 😀

[steveklabnik]

I usually do rustdoc --test path/to/crate, which isn't too bad. It can be a bit long for a big crate like std, but it's still better than building everything.

So in this case, rustdoc --test src/libcollections/lib.rs.

[nathankleyn]

@steveklabnik Ah that's awesome, thanks heaps for your help and patience! PR is ready for you and tests are green again. I'll now keep ^^ these tests running on a watch as I get through the other tasks from #29348.

[steveklabnik]

@bors: r+ rollup

Great! :) Also, there's a #rust-docs on IRC if you want to chat in realtime about issues relating to docs.

[bors]

📌 Commit da4fda4 has been approved by steveklabnik