Turn off treating warnings as errors in authoring mode using -W

Only use it in CI workflows.

Author: amotl

CHANGES.rst

@@ -6,6 +6,8 @@ Changes
 Unreleased
 ==========
 - Removed redundant ``--jobs auto`` definition
+- Turned off treating warnings as errors in authoring mode using the
+  ``-W`` option, only use it in CI workflows.
 
 2.1.6 - 2025/12/23
 ==================

common-build/rules.mk

@@ -53,8 +53,8 @@ SPHINXAUTOBUILD = $(ENV_DIR)/bin/sphinx-autobuild
 AUTOBUILD_OPTS  = --watch $(TOP_DIR) --re-ignore '^(?!.+\.(?:rst|md|mmd|html|css|js|py|conf)$$)' --open-browser --delay 0
 BUILD_DIR       = $(LOCAL_DIR)/.build
 SPHINX_ARGS     = . $(BUILD_DIR)
-SPHINX_OPTS     = -W -n --jobs auto
-SPHINX_OPTS_CI  = --keep-going
+SPHINX_OPTS     = -n --jobs auto
+SPHINX_OPTS_CI  = -W --keep-going
 RST2HTML        = $(ENV_DIR)/bin/rst2html.py
 TELEMETRY_DIR   = $(LOCAL_DIR)/telemetry
 VALE_VERSION    = 2.6.7