Add details to the templates/RSS page to clarify that the `rss.xml`
page is only generated if the `generate_rss = true` variable is set
in the site's `config.toml` page.  This information is already present
in other parts of the documentation, but is not present in the RSS page,
which could be confusing.

Add snacraft config

This allows the easy generation of snaps as requested in #227.

This commit does not add automatic generation and publication of snaps
to the Snap Store, but they can easily be generated for local/personal
use by

```
snapcraft
sudo snap install gutenberg_xxx.snap
```

Add directories with snapcraft artifacts to `.gitignore`.

Closes #277

Theme deployment

Obfuscate <!-- more --> in docs so that it doesn't get replaced

Fix #285

Fix documentation typos and minor changes:

Add Tinkering to EXAMPLES.md

- Fix some typos
- Some small changes to documentation to make it more clear
- Change the themes list from text to links

Next version

Closes #275

Closes #272

Closes #228
Closes #229

Anchor tag for summary

Close #265

Add docs for Sass processing

[WIP] Search

Make indented syntax available for SASS via the "sass" file extension