docs: add examples and keywords

[Planeshifter]

Description

What is the purpose of this pull request?

This pull request:

• adds missing C @example blocks and populates an empty keywords array, bringing three math/base/special packages in line with near-universal namespace conventions.

math/base/special/ellipj

Populates the empty keywords array in package.json with the namespace prefix (stdlib, stdmath, mathematics, math) used by 382/383 (99.7%) siblings, followed by package-specific terms in the ellipk/ellipe style (special, elliptic, jacobi, sn, cn, dn, am, amplitude, number). ellipj was the only package in lib/node_modules/@stdlib with an empty keywords array.

math/base/special/log2

Adds an @example block to the stdlib_base_log2 doc comment in src/main.c, mirroring the README C usage (stdlib_base_log2( 4.0 ) returns 2.0). Present in 374/376 (99.5%) native siblings.

math/base/special/sincosdf

Adds an @example block to the stdlib_base_sincosdf doc comment in src/main.c, mirroring sincosf and sincosd. Present in 374/376 (99.5%) native siblings.

Related Issues

Does this pull request have any related issues?

No.

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

Namespace summary. math/base/special has 383 member packages; fast is a sub-namespace and was excluded. About 90 structural and semantic features were analyzed: file tree, package.json/manifest.json keys, README section sets, the JSDoc shape of lib/{index,main,native}.js, the C doc comments in src/main.c, and the benchmark/example/test idioms. Nearly all features had a clear majority (≥75%). Two features had no clear majority and were excluded: @stdlib/string/format in benchmark/benchmark.js (73.9%) and @stdlib/random/array in examples/index.js (74.9%).

Validation. Corrections passed three independent reviews: semantic (source and README read in full), cross-reference (no test, example or tooling depends on the current state) and structural applicability. The following were deliberately excluded:

• Intentional deviations: Math.* aliases (ceil, floor, round, sqrt, ...) whose JSDoc sits on a variable rather than a function; void out-parameter C functions lacking @return; variadic *n packages and sici, which have no native addon.
• Packages with an open PR that could collide (cfloor, cceilf).
• The in-progress @stdlib/random/array benchmark migration, which changes benchmark behavior.

The diff changes only doc comments and metadata. It does not change behavior.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

• Yes
• No

If you answered "yes" above, how did you use AI assistance?

• Code generation (e.g., when writing an implementation or fixing a bug)
• Test/benchmark generation
• Documentation (including examples)
• Research and understanding

Disclosure

If you answered "yes" to using AI assistance, please provide a short disclosure indicating how you used AI assistance. This helps reviewers determine how much scrutiny to apply when reviewing your contribution. Example disclosures: "This PR was written primarily by Claude Code." or "I consulted ChatGPT to understand the codebase, but the proposed changes were fully authored manually by myself.".

This PR was written primarily by Claude Code as part of an automated cross-package drift analysis (majority vote across namespace siblings).

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🤖 Generated with Claude Code

https://claude.ai/code/session_01PrXnrxd4fshM1EZC9BNFTJ

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Generated by Claude Code

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
math/base/special/ellipj	$\\color{red}701/713$ $\\color{green}+98.32\\%$	$\\color{red}32/34$ $\\color{green}+94.12\\%$	$\\color{green}7/7$ $\\color{green}+100.00\\%$	$\\color{red}701/713$ $\\color{green}+98.32\\%$
math/base/special/log2	$\\color{green}290/290$ $\\color{green}+100.00\\%$	$\\color{green}16/16$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}290/290$ $\\color{green}+100.00\\%$
math/base/special/sincosdf	$\\color{green}252/252$ $\\color{green}+100.00\\%$	$\\color{green}7/7$ $\\color{green}+100.00\\%$	$\\color{green}3/3$ $\\color{green}+100.00\\%$	$\\color{green}252/252$ $\\color{green}+100.00\\%$

The above coverage report was generated for the changes in this PR.