firebase-ios-sdk

Edit Firebase from frameworks tech note (#5441)

* Fix up directory name, remove extra "time" in "Runtime time linking".

* Fix up relative path to svgs.

* Hmm, add img tags, again?

* Tweak width.

* Hmm, let's try <figure>.

* Grr.

* More fiddling, Markdown doesn't like <figure>.

* Yuck.

* Ditch <figure>, which doesn't want to play with GitHub Markdown.

* Jeez.

* More edits.

* Change to h3.

* Yikes.

* Now the other figure.

* Add "Figure X" to captions.

* Hmm. Now let's try commiting gDoc edits.

* Remove forum link.

* Fix title.

* Heading fixes.

* Code formatting.

* Last pass?

* Fix issue link.

* Clarify exact problem with duplicate symbols.

* Add most typical error message text