Update notes regarding ./configure and configuration

Author: keeperofdakeys

CONTRIBUTING.md

@@ -119,9 +119,10 @@ configuration used in the build process. Some options to note:
 For more options, the `config.toml` file contains commented out defaults, with
 descriptions of what each option will do.
 
-Note: Previously the `./configure` script was used for configuration, but
-is now deprecated. If you still have a `config.mk` file in your directory,
-you may need to delete it for `config.toml` to work.
+Note: Previously the `./configure` script was used to configure this
+project. It can still be used, but it's recommended to use a `config.toml`
+file. If you still have a `config.mk` file in your directory - from
+`./configure` - you may need to delete it for `config.toml` to work.
 
 ### Building
 
@@ -189,8 +190,8 @@ To learn about all possible rules you can execute, run:
 python x.py build --help --verbose
 ```
 
-Note: Previously `./configure` and `make` were used to build this project,
-but these are now deprecated.
+Note: Previously `./configure` and `make` were used to build this project.
+They are still available, but `x.py` is the recommended build system.
 
 ### Useful commands
 

README.md

@@ -36,7 +36,6 @@ Read ["Installing Rust"] from [The Book].
 
     ```sh
     $ ./x.py build && sudo ./x.py dist --install
-    $ make && sudo make install
     ```
 
     > ***Note:*** Install locations can be adjusted by copying the config file
@@ -116,9 +115,16 @@ With these dependencies installed, you can build the compiler with:
 If you're running inside of an msys shell, however, you can run:
 
 ```sh
-$ ./x.py build --build=x86_64-pc-windows-msvc && ./x.py dist --install
+$ ./x.py build --build=x86_64-pc-windows-msvc
+$ ./x.py dist --build=x86_64-pc-windows-msvc --install
 ```
 
+    > ***Note:*** The build option can also be configured by copying
+    > the config file and adjusting the `build` option under `[build]`.
+    > ```sh
+    > $ cp ./src/bootstrap/config.toml.example ./config.toml
+    > ```
+
 Currently building Rust only works with some known versions of Visual Studio. If
 you have a more recent version installed the build system doesn't understand
 then you may need to force rustbuild to use an older version. This can be done
@@ -129,6 +135,20 @@ CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.
 python x.py build
 ```
 
+### Configure and Make
+
+While it's not the recommended build system, this project also provides a
+configure script and makefile (the latter of which just invokes `x.py`).
+
+```sh
+$ ./configure
+$ make && sudo make install
+```
+
+When using the configure script, the generated config.mk` file may override the
+`config.toml` file. To go back to the `config.toml` file, delete the generated
+`config.mk` file.
+
 ## Building Documentation
 
 If you’d like to build the documentation, it’s almost the same: