Rollup merge of rust-lang#116503 - ehuss:fix-mips-tier, r=Amanieu

Update docs for mips target tier demotion.

These mips targets were demoted in rust-lang#113274, but the documentation was not updated. I have also elected to document this in the release notes for 1.72 because I think that should have been included.

RELEASES.md

@@ -229,6 +229,7 @@ Compatibility Notes
   this should only impact users of other registries, or people who don't publish
   to a registry.
   [#12291](https://github.com/rust-lang/cargo/pull/12291)
+- [Demoted `mips*-unknown-linux-gnu*` targets from host tier 2 to target tier 3 support.](https://github.com/rust-lang/rust/pull/113274)
 
 Version 1.71.1 (2023-08-03)
 ===========================

src/doc/rustc/src/platform-support.md

@@ -286,6 +286,10 @@ target | std | host | notes
 `mipsel-unknown-linux-musl` | ✓ |  | MIPS (little endian) Linux with musl libc
 `mipsel-sony-psp` | * |  | MIPS (LE) Sony PlayStation Portable (PSP)
 [`mipsel-sony-psx`](platform-support/mipsel-sony-psx.md) | * |  | MIPS (LE) Sony PlayStation 1 (PSX)
+`mips-unknown-linux-gnu` | MIPS Linux (kernel 4.4, glibc 2.23)
+`mips64-unknown-linux-gnuabi64` | MIPS64 Linux, n64 ABI (kernel 4.4, glibc 2.23)
+`mips64el-unknown-linux-gnuabi64` | MIPS64 (LE) Linux, n64 ABI (kernel 4.4, glibc 2.23)
+`mipsel-unknown-linux-gnu` | MIPS (LE) Linux (kernel 4.4, glibc 2.23)
 `mipsel-unknown-linux-uclibc` | ✓ |  | MIPS (LE) Linux with uClibc
 `mipsel-unknown-none` | * |  | Bare MIPS (LE) softfloat
 [`mipsisa32r6-unknown-linux-gnu`](platform-support/mips-release-6.md) | ? |  | 32-bit MIPS Release 6 Big Endian