Move config.toml.example to the root dir

It's way more discoverable here.

CONTRIBUTING.md

@@ -99,7 +99,7 @@ Before you can start building the compiler you need to configure the build for
 your system. In most cases, that will just mean using the defaults provided
 for Rust.
 
-To change configuration, you must copy the file `src/bootstrap/config.toml.example`
+To change configuration, you must copy the file `config.toml.example`
 to `config.toml` in the directory from which you will be running the build, and
 change the settings provided.
 

README.md

@@ -39,7 +39,7 @@ Read ["Installation"] from [The Book].
     ```
 
     > ***Note:*** Install locations can be adjusted by copying the config file
-    > from `./src/bootstrap/config.toml.example` to `./config.toml`, and
+    > from `./config.toml.example` to `./config.toml`, and
     > adjusting the `prefix` option under `[install]`. Various other options, such
     > as enabling debug information, are also supported, and are documented in
     > the config file.

src/bootstrap/README.md

@@ -80,7 +80,7 @@ handled naturally.
 
 Next, rustbuild offers a TOML-based configuration system with a `config.toml`
 file in the same location as `config.mk`. An example of this configuration can
-be found at `src/bootstrap/config.toml.example`, and the configuration file
+be found at `config.toml.example`, and the configuration file
 can also be passed as `--config path/to/config.toml` if the build system is
 being invoked manually (via the python script).
 

src/bootstrap/config.rs

@@ -35,7 +35,7 @@ use cache::{INTERNER, Interned};
 /// Note that this structure is not decoded directly into, but rather it is
 /// filled out from the decoded forms of the structs below. For documentation
 /// each field, see the corresponding fields in
-/// `src/bootstrap/config.toml.example`.
+/// `config.toml.example`.
 #[derive(Default)]
 pub struct Config {
     pub ccache: Option<String>,