Small corrections in Hot Code Push and Cordova articles

[namenotrequired]

In the Hot Code Push guide (which I wrote),

• A few small fixes and clarificationos
• Remove one paragraph that was more likely to confuse than help

In the Cordova guide,

• Add a link to the Hot Code Push guide
• Fix a code example that wasn't working

DONE (no significant changes, no new headers)

• [x] If this is a significant change, update CHANGELOG.md
• [x] Use <h2 id="foo"> instead of ## Foo for headers
• [x] Leave a blank line after each header

[lorensr]

Thank you ☺️