Examples: Audit example coverage in documentation

[rparolin]

Parent issue: #1673

Goal

Ensure all examples are referenced or linked from the published documentation.

Current state

• Some examples are referenced in getting-started.rst, others are not.
• Neither cuda_core/examples/ nor cuda_bindings/examples/ is comprehensively documented.
• Users browsing the docs may not discover examples that aren't linked.

Tasks

1. Inventory which examples are currently referenced in the docs and where.
2. Identify examples that have no documentation references.
3. Add links/references for undiscovered examples in appropriate doc pages.

Files affected

Documentation files in cuda_core/docs/ and cuda_bindings/docs/, plus all 25 example files listed in #1673.

[mdboom]

Seems like a good use of a sphinx plugin to just automatically glob all of the examples.