doc: add cmake SPHINXOPTS_EXTRA option

Add a new CMake option to append options to SPHINXOPTS. This allows us
to easily extend default SPHINXOPTS. This patch also restores the "-j
auto" option in CI (now that we use a custom runner).

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

.github/workflows/doc-build.yml

@@ -85,7 +85,7 @@ jobs:
           DOC_TARGET="html"
         fi
 
-        DOC_TAG=${DOC_TAG} SPHINXOPTS="-q -W --keep-going -t publish" make -C doc ${DOC_TARGET}
+        DOC_TAG=${DOC_TAG} SPHINXOPTS_EXTRA="-q -t publish" make -C doc ${DOC_TARGET}
 
     - name: compress-docs
       run: |

doc/CMakeLists.txt

@@ -13,12 +13,14 @@ message(STATUS "Zephyr base: ${ZEPHYR_BASE}")
 # Options
 
 set(SPHINXOPTS "-j auto -W --keep-going" CACHE STRING "Default Sphinx Options")
+set(SPHINXOPTS_EXTRA "" CACHE STRING "Extra Sphinx Options (added to defaults)")
 set(LATEXMKOPTS "-halt-on-error -no-shell-escape" CACHE STRING "Default latexmk options")
 set(DT_TURBO_MODE OFF CACHE BOOL "Enable DT turbo mode")
 set(DOC_TAG "development" CACHE STRING "Documentation tag")
 set(DTS_ROOTS "${ZEPHYR_BASE}" CACHE STRING "DT bindings root folders")
 
 separate_arguments(SPHINXOPTS)
+separate_arguments(SPHINXOPTS_EXTRA)
 separate_arguments(LATEXMKOPTS)
 
 #-------------------------------------------------------------------------------
@@ -145,6 +147,7 @@ add_doc_target(
     -w ${DOCS_BUILD_DIR}/html.log
     -t ${DOC_TAG}
     ${SPHINXOPTS}
+    ${SPHINXOPTS_EXTRA}
     ${DOCS_SRC_DIR}
     ${DOCS_HTML_DIR}
   USES_TERMINAL
@@ -173,6 +176,7 @@ add_doc_target(
     -t ${DOC_TAG}
     -t svgconvert
     ${SPHINXOPTS}
+    ${SPHINXOPTS_EXTRA}
     ${DOCS_SRC_DIR}
     ${DOCS_LATEX_DIR}
   USES_TERMINAL
@@ -223,6 +227,7 @@ add_doc_target(
     -w ${DOCS_BUILD_DIR}/linkcheck.log
     -t ${DOC_TAG}
     ${SPHINXOPTS}
+    ${SPHINXOPTS_EXTRA}
     ${DOCS_SRC_DIR}
     ${DOCS_LINKCHECK_DIR}
   USES_TERMINAL