[AIR] Fixed broken doc links, grammar and misleading comments

[jetbrains-air]

Small, self-contained documentation fixes found by scanning the codebase. No behavior changes.

Broken / obsolete links (verified over HTTP)

Where	Was	Now
KODEX_KDOC_PREPROCESSING.md (×2)	plugins.jetbrains.com/plugin/26250 → 404	/plugin/27473 (nl.jolanrensen.kodex, the current KoDEx plugin)
dataframe-jupyter/README.md (×2), dataframe-json/README.md	usage-with-kotlin-notebook-plugin.html → 404	kotlin-dataframe-features-in-kotlin-notebook.html
dataframe-jupyter/README.md (×2)	gettingstartedjupyternotebook.html (obsolete, now only a redirect stub)	setupjupyter.html

Broken section anchors

apiLevels.md links to SetupGradle.md#kotlin-dataframe-compiler-plugin and SetupMaven.md#kotlin-dataframe-compiler-plugin, but neither anchor existed, so both links silently landed at the top of the page. Added {id="kotlin-dataframe-compiler-plugin"} to the ### 1. Add the plugin heading in both files — the same explicit-id pattern already used in Modules.md and DataSchemaGenerationMethods.md.

Grammar / wording

• api/joinWith.kt — "combinations of rows … that satisfies" → "that satisfy" (subject-verb agreement); "simple values equality" → "simple value equality".
• ConvertingMismatch.kt (×2) — "is not presented in actual data" → "is not present in actual data".
• concepts/concepts.md — "are presented in another dataframe" → "are present in"; "misspell column name" → "misspell a column name"; "mess up with its type" → "mess up its type".
• mysqlH2Test.kt — "should not contain the system names itself" → "themselves".
• pivot.md — "cells where intersection of column and row keys" → "where the intersection of".
• schemasGradle.md — added missing articles and fixed word order: "Relative path by default is resolved to …" → "By default, a relative path is resolved against …".

Spelling consistency

Normalized the 4 remaining British spellings to the American form used everywhere else in the repo (recognized appears 34×, recognised 2×): h2Test.kt, readSqlTypeMapping_DuckDB.md, readSqlTypeMapping_SQLite.md (×2). Test function names containing unrecognised were left alone deliberately.

Noted but not fixed

The docs show four remote-read examples, of which three point at files that aren't published: resources/example.json, example.xlsx and example.feather all 404 (example.csv is fine). Fixing that means publishing the files, not editing text, so it's out of scope here — flagging it for a maintainer.

Verification

Re-ran the link/anchor checkers after the change: 0 broken anchors and 0 broken .md links remain across docs/StardustDocs/topics, and both replacement URLs return 200. Only comments, KDoc, string literals and markdown prose were touched — no public signatures, so no apiDump change. All edited markdown lines were confirmed to sit outside the korro <!---FUN--> blocks that the CI bot regenerates. Note: Gradle cannot resolve plugins in this sandbox (no network to the plugin repo), so ktlint/tests were not run here; the one Kotlin comment line that grew is 130 chars, in line with the 1004 over-120 comment lines already on master (ktlint's line-length rule does not flag comments in this project).

Produced by Air Automations. Name: Bi-weekly Grammar Nazi / Run: https://air.jetbrains.cloud/org/05cf1a7f-6ab5-713b-abd3-29d0c8a05e2d/automations/a9009d9e-63e7-4730-801c-185f5785b6bd?run=73a8b607-9770-4130-b1ea-cfdf67dfcc60

🤖 Generated with Claude Code

[jetbrains-air]

Lovely little cleanup — every link, anchor and wording fix checks out, so this is good to merge!

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Produced by Air Automations. Name: AI Review / Run: https://air.jetbrains.cloud/org/05cf1a7f-6ab5-713b-abd3-29d0c8a05e2d/automations/8daf2412-0b6c-4433-90c0-b40ab5aebcdb?run=255b9e87-7bdc-47ca-8f8c-c2e0a42bfa8a