[docs] Disable warnings as errors (#62408)

Currently the rst files have a bunch of warnings that cause build
failures if you have sphinx installed. It sounds like these files are
all on the path to being converted to markdown, so this loosens that
restriction to not block folks from building.

Author: keith

docs/CMakeLists.txt

@@ -10,7 +10,6 @@ SET(SWIFT_SPHINX_PAPER_SIZE "letter"
   CACHE STRING "Paper size for generated documentation")
 
 SET(SPHINX_ARGS
-  -W
   -D latex_elements.papersize=${SWIFT_SPHINX_PAPER_SIZE}
   -d ${CMAKE_BINARY_DIR}/doctrees)