Fix a spelling error: Unqeual -> Unequal

Change-Id: I5bcd78177980f9defc5ecff913cd1d896e36b23d

docs.cmake

diff --git a/docs.cmake b/docs.cmake
index 0d8db92..0d7b4cf 100644
--- a/docs.cmake
+++ b/docs.cmake
@@ -223,7 +223,7 @@
   list(LENGTH AOM_DOXYGEN_EXAMPLE_SOURCES num_sources)
   list(LENGTH AOM_DOXYGEN_EXAMPLE_DESCRIPTIONS num_descs)
   if(NOT ${num_sources} EQUAL ${num_descs})
-    message(FATAL_ERROR "Unqeual example and description totals.")
+    message(FATAL_ERROR "Unequal example and description totals.")
   endif()
 
   # Take the list of examples and produce example_basename.dox for each file in