docs: add patents.txt

Thanks to José Fonseca for writing this.

docs/patents.txt

@@ -0,0 +1,31 @@
+ARB_texture_float:
+
+    Silicon Graphics, Inc. owns US Patent #6,650,327, issued November 18,
+    2003 [1].
+
+    SGI believes this patent contains necessary IP for graphics systems
+    implementing floating point rasterization and floating point
+    framebuffer capabilities described in ARB_texture_float extension, and
+    will discuss licensing on RAND terms, on an individual basis with
+    companies wishing to use this IP in the context of conformant OpenGL
+    implementations [2].
+
+    The source code to implement ARB_texture_float extension is included
+    and can be toggled on at compile time only by those who purchased
+    a license from SGI, or are in a country where the patent does not
+    apply.
+
+    The software is provided "as is", without warranty of any kind, express
+    or implied, including but not limited to the warranties of
+    merchantability, fitness for a particular purpose and noninfringement.
+    In no event shall the authors or copyright holders be liable for any
+    claim, damages or other liability, whether in an action of contract,
+    tort or otherwise, arising from, out of or in connection with the
+    software or the use or other dealings in the software.
+
+    You should contact a lawyer or SGI's legal department if you want to
+    enable this extension.
+
+
+[1] http://www.google.com/patents/about?id=mIIOAAAAEBAJ&dq=6650327
+[2] http://www.opengl.org/registry/specs/ARB/texture_float.txt