docs(contrib): Replace architecture with redirects

I also went back to pages moved in rust-lang#11869 and added redirects for those
as well.

src/doc/contrib/book.toml

@@ -8,3 +8,10 @@ git-repository-url = "https://github.com/rust-lang/cargo/tree/master/src/doc/con
 
 [output.html.redirect]
 "/apidoc/cargo/index.html" = "https://doc.rust-lang.org/nightly/nightly-rustc/cargo/"
+"/architecture/index.html" = "../implementation/architecture.html"
+"/architecture/console.html" = "../implementation/console.html"
+"/architecture/subcommands.html" = "../implementation/subcommands.html"
+"/architecture/codebase.html" = "https://doc.rust-lang.org/nightly/nightly-rustc/cargo"
+"/architecture/compilation.html" = "https://doc.rust-lang.org/nightly/nightly-rustc/cargo"
+"/architecture/files.html" = "https://doc.rust-lang.org/nightly/nightly-rustc/cargo"
+"/architecture/packages.html" = "https://doc.rust-lang.org/nightly/nightly-rustc/cargo"

src/doc/contrib/src/SUMMARY.md

@@ -13,11 +13,6 @@
     - [Console Output](./implementation/console.md)
     - [Filesystem](./implementation/filesystem.md)
     - [Debugging](./implementation/debugging.md)
-- [Architecture](./architecture/index.md)
-    - [Codebase Overview](./architecture/codebase.md)
-    - [Packages and Resolution](./architecture/packages.md)
-    - [Compilation](./architecture/compilation.md)
-    - [Files](./architecture/files.md)
 - [Tests](./tests/index.md)
     - [Running Tests](./tests/running.md)
     - [Writing Tests](./tests/writing.md)