Do not generate Sphinx doc for OpenCL/SPV exts

Do not generate Sphinx documentation for the OpenCL or SPIR-V
extensions because they are written in AsciiDoc, which Spinx does not
support well.  Instead, link to their GitHub location, and readers can
read GitHub's rendering of the AsciiDoc documents.  This is the same
thing we do already for the SYCL extension specifications.

Author: gmlueck

sycl/doc/conf.py

@@ -46,8 +46,12 @@
 # The suffix of source filenames.
 source_suffix = ['.rst', '.md']
 
-# Extensions are mostly in asciidoc which has poor support in Sphinx
-exclude_patterns = ['extensions/*']
+exclude_patterns = [
+    # Extensions are mostly in asciidoc which has poor support in Sphinx.
+    'extensions/*',
+    'design/opencl-extensions/*',
+    'design/spirv-extensions/*'
+]
 
 suppress_warnings = [ 'misc.highlighting_failure' ]
 

sycl/doc/index.rst

@@ -42,6 +42,8 @@ Developing oneAPI DPC++ Compiler
    ITTAnnotations
    DeviceGlobal
    CompileTimeProperties
+   New OpenCL Extensions <https://github.com/intel/llvm/tree/sycl/sycl/doc/design/opencl-extensions>
+   New SPIR-V Extensions <https://github.com/intel/llvm/tree/sycl/sycl/doc/design/spirv-extensions>
 
 Development BKMs
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