add blog post about docs.rs changed default targets

Author: syphar

content/docs-rs-changed-default-targets.md

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+path = "2025/10/15/docsrs-changed-default-targets"
+title = "docs.rs: changed default targets"
+authors = ["Denis Cornehl"]
+
+[extra]
+team = "the docs.rs team"
+team_url = "https://rust-lang.org/governance/teams/dev-tools/#team-docs-rs"
++++
+
+With Apple's transition from x86_64 to its own silicon (ARM64), the Rust project
+has updated its platform support tiers.
+
+Consequently, the `aarch64-apple-darwin` target has been promoted to Tier 1,
+while the `x86_64-apple-darwin` target has been demoted to Tier 2. You can read
+more about this change in
+[RFC 3671](https://github.com/rust-lang/rfcs/pull/3671) and
+[RFC 3841](https://github.com/rust-lang/rfcs/pull/3841).
+
+To align with this ecosystem shift, docs.rs is updating its default build
+targets.
+
+Crates can provide [docs.rs metadata](https://docs.rs/about/metadata) to specify
+which targets to build for. If this metadata is not provided, docs.rs uses a
+default list of targets. We are now switching the default macOS target in this
+list from `x86_64-apple-darwin` to `aarch64-apple-darwin`.
+
+The new default target list is:
+
+- `x86_64-unknown-linux-gnu`
+- `aarch64-apple-darwin` (previously: `x86_64-apple-darwin`)
+- `x86_64-pc-windows-msvc`
+- `i686-unknown-linux-gnu`
+- `i686-pc-windows-msvc`
+
+## If your crate requires the old target list
+
+If your crate needs to be built for the previous default target list, you can
+explicitly define it using [docs.rs metadata](https://docs.rs/about/metadata) in
+your `Cargo.toml`:
+
+```toml
+[package.metadata.docs.rs]
+targets = [
+    "x86_64-unknown-linux-gnu",
+    "x86_64-apple-darwin",
+    "x86_64-pc-windows-msvc",
+    "i686-unknown-linux-gnu",
+    "i686-pc-windows-msvc"
+]
+```