Do not completely hide platfrom-specific info for other platforms

[SimonSapin]

Steps to reproduce:

• Use a web browser on Linux
• Google "rust msvc"
• See that the first result is https://www.rust-lang.org/install.html, with preview “On Windows, Rust additionally requires the C++ build tools for Visual Studio 2013 or later. ” This is relevant to my interests.
• Click that link

Actual result:

The previewed sentence and its context are nowhere to be found, unless I use View Source and squint to read HTML in my head.

Expected result:

Platform-specific content that the site guessed is "irrelevant" should still be accessible somehow, perhaps with un-collapsible sections.

[eddyp]

I agree.

In the same vein, for cross compilation to less capable targets or tier2, 2.5, 3 (e.g. bare metal embedded systems, say a platform with CortexM7) there might be specific restrictions such as no std support, or maybe only gdb is available, but not lldb etc. information which should be available, even if in a collapsed section.

One example I can think of now, is that it is not obvious how to update/enable the tool chains for such targets, even if I can see on the https://forge.rust-lang.org/platform-support.html page they are supported.