Update to use exclude_patterns

The exclude_patterns setting replaces exclude_trees and unused_docs,
which modern versions of Sphinx no longer support.  Since
exclude_patterns was added in Sphinx 1.0, document that version as a
requirement.

This change fixes warnings about unlinked documents.

README.md

@@ -12,8 +12,9 @@ once ready.
 You will need the Sphinx documentation tool installed to process the
 documentation.  Confusingly there are several open source projects called
 "Sphinx" - see http://sphinx-doc.org/install.html for tips on installing
-the one you want.  We aren't certain exactly what version is needed - it
-seems Sphinx 0.6.4 is too old but 1.1.3 is new enough.
+the one you want.  We aren't certain exactly what version is needed - at
+least Sphinx 1.0.0 is needed, but the oldest we've actually tested with
+recently was Sphinx 1.1.3.
 
 You can generate versions for different programming languages (with translated
 examples and adjustments to the text).  For full details see `make help`

conf.py

@@ -89,12 +89,9 @@
 # Else, today_fmt is used as the format for a strftime call.
 #today_fmt = '%B %d, %Y'
 
-# List of documents that shouldn't be included in the build.
-#unused_docs = []
-
-# List of directories, relative to source directory, that shouldn't be searched
-# for source files.
-exclude_trees = ['_build', 'attic', 'language_specific']
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+exclude_patterns = ['_build', 'attic', 'language_specific']
 
 # The reST default role (used for this markup: `text`) to use for all documents.
 #default_role = None