use docs/requirements.in as well

.renovaterc.json

@@ -9,7 +9,7 @@
     }
   ],
   "pip-compile": {
-    "fileMatch": ["^requirements\\.in$", "^docs/requirements\\.in$"]
+    "fileMatch": ["(^|/)requirements\\.in$"]
   },
   "pip_requirements": {
     "enabled": false

docs/requirements.in

@@ -5,7 +5,7 @@
 # Please add developer dependencies which are not needed to install
 # Stackspin to requirements-dev.txt!
 #
-recommonmark
-sphinx
-sphinx-design
-sphinx-rtd-theme
+recommonmark==0.7.0
+sphinx==4.4.0
+sphinx-design==0.0.13
+sphinx-rtd-theme==1.0.0