Remove tiers of support (JuliaLang#32022)

The tiers of support are now maintained in one place, i.e. on the downloads page on the website. It was difficult to have an accurate list of tiers for master, and much simpler to have support tiers for the latest stable release instead. Thus, the downloads page is the right place to host this information and curate it.

README.md

@@ -52,7 +52,10 @@ helpful to start contributing to the Julia codebase.
 
 If you would rather not compile the latest Julia from source,
 platform-specific tarballs with pre-compiled binaries are also
-[available for download](https://julialang.org/downloads/).
+[available for download](https://julialang.org/downloads/). The
+downloads page also provides details on the
+[different tiers of support](https://julialang.org/downloads/#support-tiers)
+for OS and platform combinations.
 
 If everything works correctly, you will see a Julia banner and an
 interactive prompt into which you can enter expressions for
@@ -64,45 +67,6 @@ installations are neither maintained nor endorsed by the Julia
 project. They may be outdated, broken and/or unmaintained. We
 recommend you use the official Julia binaries instead.
 
-## Currently Supported Platforms
-
-| Operating System | Architecture | CI | Binaries | Support Level |
-|:----------------:|:----------------:|:--:|:--------:|:-------------:|
-| macOS 10.8+ | x86-64 (64-bit) | ✓ | ✓ | Tier 1 |
-| Windows 7+ | x86-64 (64-bit) | ✓ | ✓ | Tier 1 |
-| | i686 (32-bit) | ✓ | ✓ | Tier 1 |
-| FreeBSD 11.0+ | x86-64 (64-bit) | [✓](https://build.julialang.org/#/builders/68) | ✓ | Tier 1 |
-| Linux 2.6.18+ | x86-64 (64-bit) | ✓ | ✓ | Tier 1 |
-| | i686 (32-bit) | ✓ | ✓ | Tier 1 |
-| | ARM v7 (32-bit) | | | Tier 3 |
-| | ARM v8 (64-bit) | | | Tier 3 |
-| | x86-64 musl libc | | | Tier 3 |
-| | PowerPC (64-bit) | | | Tier 4 |
-| | PTX (64-bit) | [✓](https://gitlab.com/JuliaGPU/CUDAnative.jl/pipelines) | | [External](https://github.com/JuliaGPU/CUDAnative.jl) |
-
-All systems marked with ✓ for CI are tested using continuous integration for every commit.
-Systems with ✓ for binaries have official binaries available on the
-[downloads](https://julialang.org/downloads) page and are tested regularly.
-The PTX backend is supported by the [JuliaGPU](https://github.com/JuliaGPU) organization and
-requires the [CUDAnative.jl](https://github.com/JuliaGPU/CUDAnative.jl) package.
-
-### Support Tiers
-
-* Tier 1: Julia is guaranteed to build from source and pass all tests on these platforms
- when built with default options. Official binaries are available for releases and CI is
- run on every commit.
-
-* Tier 2: Julia is guaranteed to build from source using default build options, but may
- or may not pass all tests. Official binaries are available on a case-by-case basis.
-
-* Tier 3: Julia may or may not build. If it does, it is unlikely to pass tests.
-
-* Tier 4: Julia is known not to build.
-
-It is possible that Julia will build and work on other platforms too,
-and we're always looking to improve our platform coverage. If you're
-using Julia on a platform not listed here, let us know!
-
 ## Building Julia
 
 First, make sure you have all the [required