Fix various dangling URLs.

Update URLs to various things that have been renamed or moved.

Fixes #403.

Author: sunfishcode

README.md

@@ -37,6 +37,6 @@ To contribute to any of these repositories, see the Community Group's
 [formal spec]: spec/
 [W3C WebAssembly Community Group]: https://www.w3.org/community/webassembly/
 [Contributing Guidelines]: https://webassembly.org/community/contributing/
-[WASI Preview 2]: https://github.com/WebAssembly/WASI/tree/main/preview2
-[WASI Preview 3]: https://github.com/WebAssembly/WASI/tree/main/preview2#looking-forward-to-preview-3
+[WASI Preview 2]: https://github.com/WebAssembly/WASI/tree/main/wasip2#readme
+[WASI Preview 3]: https://github.com/WebAssembly/WASI/tree/main/wasip2#looking-forward-to-preview-3
 [Async Support]: https://docs.google.com/presentation/d/1MNVOZ8hdofO3tI0szg_i-Yoy0N2QPU2C--LzVuoGSlE/edit?usp=share_link

design/high-level/FAQ.md

@@ -24,7 +24,7 @@ custom scenarios, this might be appropriate.
 
 ### Does the Component Model force every (module | package | library) to have a separate memory?
 
-No, as described in [Linking.md](Linking.md), the Component Model supports a
+No, as described in [Linking.md](../mvp/Linking.md), the Component Model supports a
 combination of "shared-everything" and "shared-nothing" linking, allowing
 developers and producer toolchains to choose the appropriate kind of linking
 to use in a particular situation.

design/mvp/Explainer.md

@@ -2224,12 +2224,12 @@ For some use-case-focused, worked examples, see:
 [interface-types]: https://github.com/WebAssembly/interface-types/blob/main/proposals/interface-types/Explainer.md
 [type-imports]: https://github.com/WebAssembly/proposal-type-imports/blob/master/proposals/type-imports/Overview.md
 [exception-handling]: https://github.com/WebAssembly/exception-handling/blob/main/proposals/exception-handling/Exceptions.md
-[stack-switching]: https://github.com/WebAssembly/stack-switching/blob/main/proposals/stack-switching/Overview.md
+[stack-switching]: https://github.com/WebAssembly/stack-switching/blob/main/proposals/stack-switching/Explainer.md
 [esm-integration]: https://github.com/WebAssembly/esm-integration/tree/main/proposals/esm-integration
 [gc]: https://github.com/WebAssembly/gc/blob/main/proposals/gc/MVP.md
 [`rectype`]: https://webassembly.github.io/gc/core/text/types.html#text-rectype
 [shared-everything-threads]: https://github.com/WebAssembly/shared-everything-threads
-[WASI Preview 2]: https://github.com/WebAssembly/WASI/tree/main/preview2
+[WASI Preview 2]: https://github.com/WebAssembly/WASI/tree/main/wasip2#readme
 
 [Adapter Functions]: FutureFeatures.md#custom-abis-via-adapter-functions
 [Canonical ABI explainer]: CanonicalABI.md