Updated documentation for the script that builds the OSX installer.

Mac/BuildScript/README.txt

@@ -8,15 +8,47 @@ $DESTROOT, massages that installation to remove .pyc files and such, creates
 an Installer package from the installation plus other files in ``resources`` 
 and ``scripts`` and placed that on a ``.dmg`` disk image.
 
-Here are the steps you ned to follow to build a MacPython installer:
+Prerequisites
+-------------
 
-- Run ``./build-installer.py``. Optionally you can pass a number of arguments
-  to specify locations of various files. Please see the top of
+* A MacOS X 10.4 (or later)
+
+* XCode 2.2 (or later), with the universal SDK
+
+* No Fink (in ``/sw``) or DarwinPorts (in ``/opt/local``), those could
+  interfere with the build.
+
+* The documentation for the release must be available on python.org
+  because it is included in the installer.
+
+
+The Recipe
+----------
+
+Here are the steps you need to follow to build a MacPython installer:
+
+*  Run ``./build-installer.py``. Optionally you can pass a number of arguments
+   to specify locations of various files. Please see the top of
   ``build-installer.py`` for its usage.
-- When done the script will tell you where the DMG image is.
 
-The script needs to be run on Mac OS X 10.4 with Xcode 2.2 or later and
-the 10.4u SDK.
+  Running this script takes some time, I will not only build Python itself
+  but also some 3th-party libraries that are needed for extensions.
+
+* When done the script will tell you where the DMG image is (by default
+  somewhere in ``/tmp/_py``).
+
+Testing
+-------
+
+The resulting binaries should work on MacOSX 10.3.9 or later. I usually run
+the installer on a 10.3.9, a 10.4.x PPC and a 10.4.x Intel system and then
+run the testsuite to make sure.
+
+
+Announcements
+-------------
+
+(This is mostly of historic interest)
 
 When all is done, announcements can be posted to at least the following
 places: