Small improvements for `Architecture.md`, `TreeExample.md`

[chykon]

Description & Motivation

It is proposed to make small changes to the Architecture.md and TreeExample.md files:

• Rename files to follow snake_case
• Fix typos, remove extra spaces
• Update code in TreeExample.md (updated code is taken from example/tree.dart)
• Update generated SystemVerilog in TreeExample.md
• Update links to renamed files

Related Issue(s)

No.

Testing

Not required.

Backwards-compatibility

Is this a breaking change that will not be backwards-compatible? If yes, how so?

Old links to renamed files will no longer work.

Documentation

Does the change require any updates to documentation? If so, where? Are they included?

The proposed changes for Architecture.md and TreeExample.md do not affect the actual content.

[chykon]

Need to restart CI after some time due to external links check failure.

[chykon]

Because README.md currently cannot use relative links (this results in an error when checking the documentation) (https://github.com/dart-lang/dartdoc/issues/1096), there was a chicken-and-egg problem with checking links. It is proposed to temporarily add the path to the new file to the ignore list so that the PR will complete successfully.

If such a solution is suitable, then we will need to remember to remove the path from the ignore list.