Remove -r flag

Author: dstansby

.circleci/config.yml

@@ -77,7 +77,7 @@ doc-run: &doc-build
   name: Build documentation
   command: |
     make html O=-T
-    rm -rv build/html/_sources
+    rm -r build/html/_sources
   working_directory: doc
 
 doc-bundle-run: &doc-bundle