Restructure & update CONTRIBUTING.md

Author: wilzbach

CONTRIBUTING.md

@@ -11,7 +11,7 @@ Make sure you have these prerequisites working:
 * The C++ compiler for your platform (invokable as `gcc`)
 * Optional: `latex` for building the pdf documentation
 * Optional: `kindlegen` for building the Kindle documentation
-* If you're running OSX, make sure you have some version of `libevent` installed
+* If you're running OSX, make sure you have some version of `libevent` installed (needed for Ddox)
 
 ## Getting the code
 
@@ -23,9 +23,12 @@ code:
 cd $R
 git clone https://github.com/dlang/dlang.org
 git clone https://github.com/dlang/dmd
+git clone https://github.com/dlang/druntime
+git clone https://github.com/dlang/phobos
 ```
 
 The `dmd` compiler is needed for processing the documentation.
+`druntime` and `phobos` are only needed if their docs should be built.
 
 ## Building the main site
 
@@ -54,48 +57,52 @@ currently being worked on. The "release" version is built with the "release"
 compiler, and the current version is built with the current compiler (which we
 already have from the previous step).
 
-### Building the release libraries
+### Building the `prerelease` libraries
 
-Fortunately there's no need to fumble with version numbers and git tags etc.;
-all is automated. Run this command:
+The more interesting stuff to build is the prerelease libraries because in all
+likelihood that's what needs looking at and testing.
 
 ```
 cd $R/dlang.org
-make -f posix.mak druntime-release
-make -f posix.mak phobos-release
-make -f posix.mak apidocs-release
+make -f posix.mak docs-prerelease
 ```
 
-These commands tell you the release being built in their first line of output.
-Then they proceed and clone the appropriate release for `dmd`, `druntime`, and
-`phobos`. After all commands have been executed, the following directories will
-be present in `$R`: `dlang.org`, `dmd`, `dmd-2.083.2`, `druntime-2.083.2`, and
-`phobos-2.083.2`. Note that the actual release number may not be `2.083.2`, but
-should be the same for all three directories.
+If you only want to build a specific part (e.g. Phobos), run:
 
-The output is in `$R/dlang.org/web/phobos` and `$R/dlang.org/web/library`.
+```
+cd $R/dlang.org
+make -f posix.mak phobos-prerelease
+```
 
-### Building the prerelease libraries
+(`docs-prerelease` is a shorthand for `dmd-prerelease`, `druntime-prerelease`, `phobos-releas` and `apidocs-prerelease`)
 
-The more interesting stuff to build is the prerelease libraries because in all
-likelihood that's what needs looking at and testing. To do that two more
-repositories containing the core and standard libraries are needed: `druntime`
-and `phobos`:
+The output is in `$R/dlang.org/web/phobos-prerelease` and
+`$R/dlang.org/web/library-prerelease`.
+
+### Building the `release` libraries
+
+Fortunately there's no need to fumble with version numbers and git tags etc.;
+all is automated. Run this command:
 
 ```
-cd $R
-git clone https://github.com/dlang/druntime
-git clone https://github.com/dlang/phobos
+cd $R/dlang.org
+make -f posix.mak docs-release
 ```
 
-With the new repos in tow this builds the prerelease libraries:
+If you only want to build a specific part (e.g. Phobos), run:
 
 ```
 cd $R/dlang.org
-make -f posix.mak druntime-prerelease
-make -f posix.mak phobos-prerelease
-make -f posix.mak apidocs-prerelease
+make -f posix.mak phobos-release
 ```
 
-The output is in `$R/dlang.org/web/phobos-prerelease` and
-`$R/dlang.org/web/library-prerelease`.
+(`docs-release` is a shorthand for `dmd-release`, `druntime-release`, `phobos-releas` and `apidocs-release`)
+
+These commands tell you the release being built in their first line of output.
+Then they proceed and clone the appropriate release for `dmd`, `druntime`, and
+`phobos`. After all commands have been executed, the following directories will
+be present in `$R`: `dlang.org`, `dmd`, `dmd-2.083.2`, `druntime-2.083.2`, and
+`phobos-2.083.2`. Note that the actual release number may not be `2.083.2`, but
+should be the same for all three directories.
+
+The output is in `$R/dlang.org/web/phobos` and `$R/dlang.org/web/library`.