docs: add missing load() statements in examples

[abishekgiri]

What does this PR do?

This PR adds missing load() statements to documentation examples that reference
rules or symbols without showing how they are imported.

Several examples currently assume implicit knowledge of where rules are defined,
which can be confusing for new users.

---

What’s included?

• Added the appropriate load() statements to affected examples
• No behavioral or semantic changes to the documented examples
• Improves copy-paste usability and clarity

---

Why is this useful?

Without explicit load() statements, examples may not work as written and can
lead to confusion for users learning Bazel rules and macros.

This change makes the documentation more self-contained and accurate.

---

Verification

• Manually reviewed updated examples for correctness and consistency
• Confirmed all added load() statements match the rules used in each example

---

Fixes #16001

[gemini-code-assist]

Code Review

This pull request adds missing load() statements to code examples in the documentation, which improves their accuracy and makes them easier for users to copy and use directly. The changes are correct and well-targeted. No issues were found during the review.

[meteorcloudy]

We should update those examples to use MODULE.bazel

@ahumesky