Fix runnable Zola example Reddit config

[EthanPlant]

Problem

The v0.1.0 Zola example config uses:

subreddit = "/r/example"

The documented preferred form elsewhere is:

subreddit = "reddit"

Even after Reddit normalization is fixed (#1), the runnable example should use the cleanest recommended form. Examples should teach the boring path, not the weird edge case.

Expected behaviour

The example project should use:

[reddit]
kind = "link"
subreddit = "example"
title_template = "{title}"
comment_template = """
{excerpt}

Originally published here:
{url}
"""

Done When

• examples/zola/elsewhere.toml uses subreddit = "example"
• README example remains consistent with the runnable example
• docs/configuration.md and docs/renderers.md describe accepted forms clearly
• running the example produces Subreddit: r/example