Add prerequisite page

[skade]

Fixes #722

Currently only includes instructions for Windows, I didn't have a Linux machine available.

Taken from @yoshuawuyts instructions.

[JohnTitor]

Left some thoughts:

• I'd mention this chapter in somewhere of "How to Build and Run the Compiler"
• I'd also have a link to rust-lang/rust README since it should be up-to-date than here

[mark-i-m]

Thanks @skade! This is definitely good content to have!

[mark-i-m]

@skade If you want, you can copy the hardware requirements section from my PR #731

[mark-i-m]

I think I've addressed the outstanding review comments (sorry, I hope you don't mind, @skade). I accidentally referred to this page from #731, so it would be great to merge this and fix the link....

[mark-i-m]

I don't understand the current CI failure...

[jyn514]

Works for me locally. Not sure what's going on in CI.

$ mdbook build
2020-06-18 19:49:22 [INFO] (mdbook::book): Book building has started
2020-06-18 19:49:22 [INFO] (mdbook::book): Running the html backend
2020-06-18 19:49:24 [INFO] (mdbook::book): Running the linkcheck backend
2020-06-18 19:49:24 [INFO] (mdbook::renderer): Invoking the "linkcheck" renderer
$

You can reproduce by adding github to the ignore list:

$ git diff
diff --git a/book.toml b/book.toml
index c342c38..f0dc6f5 100644
--- a/book.toml
+++ b/book.toml
@@ -15,6 +15,6 @@ level = 1
 
 [output.linkcheck]
 follow-web-links = true
-exclude = [ "crates\\.io", "gcc\\.godbolt\\.org", "youtube\\.com", "youtu\\.be", "dl\\.acm\\.org", "cs\\.bgu\\.ac\\.il" ]
+exclude = [ "github.com", "crates\\.io", "gcc\\.godbolt\\.org", "youtube\\.com", "youtu\\.be", "dl\\.acm\\.org", "cs\\.bgu\\.ac\\.il" ]
 cache-timeout = 86400
 warning-policy = "error"

[mark-i-m]

I think CI should finally pass 🤞

Thanks @skade!