Made sure to remove the .doc directories first, fixed exec

Tools/Documentation/make_headers.sh

@@ -2,10 +2,20 @@
 #
 # NOTE: The working directory should be the main capp directory when this script is run
 
+echo "Preprocessing source files..."
+
+if [ -d AppKit.doc ]; then
+    rm -rf AppKit.doc
+fi
+
+if [ -d Foundation.doc ]; then
+    rm -rf Foundation.doc
+fi
+
 cp -r AppKit AppKit.doc
 cp -r Foundation Foundation.doc
 
 find AppKit.doc -name *.j -exec sed -e '/@import.*/ d' -i '' {} \;
 find Foundation.doc -name *.j -exec sed -e '/@import.*/ d' -i '' {} \;
 
-exec Tools/Documentation/make_headers.rb
+exec Tools/Documentation/make_headers