Add more doc-valid-idents
* "AccessKit" is a commonly used accessibility toolkit used in Rust GUIs.
* "CoreFoundation", "CoreGraphics", "CoreText" are frameworks on Apple OSes.
* "Direct2D", "Direct3D", "DirectWrite" are frameworks on Windows
* "PostScript" is a programming language and is mentioned when talking about text and vector graphics.
* "OpenAL" is an audio framework / API.
* "OpenType" is a font format (TrueType is already mentioned).
* "WebRTC", "WebSocket", "WebTransport" are web networking technologies.
* "NetBSD" and "OpenBSD" are like the already included FreeBSD.
changelog: [`doc_markdown`]: Add AccessKit, CoreFoundation, CoreGraphics, CoreText, Direct2D, Direct3D, DirectWrite, PostScript, OpenAL, OpenType, WebRTC, WebSocket, WebTransport, NetBSD, and OpenBSD to `doc-valid-idents`.