Remove redundant --keep-going

Co-authored-by: Andrew Murray <3112309+radarhere@users.noreply.github.com>

Author: hugovk

docs/Makefile

@@ -4,7 +4,7 @@
 # You can set these variables from the command line.
 PYTHON        = python3
 SPHINXBUILD   = $(PYTHON) -m sphinx.cmd.build
-SPHINXOPTS    = --fail-on-warning --keep-going
+SPHINXOPTS    = --fail-on-warning
 BUILDDIR      = _build
 BUILDER       = html
 JOBS          = auto