update user guide

jupysketch-doc/site/yamlsketcher/index.html

@@ -440,12 +440,13 @@ Parts          ::= "-" " " "parts:\n" Comment? Par
 Part           ::= Part_Name Shapes
 Part_Name      ::= INDENT "-" " " "name: " Identifier Comment? "\n" DEDENT
 Shapes         ::= INDENT " " " " "shapes:\n" Comment? Shape+ DEDENT
-Shape          ::= Expression| DoAction | SketchObject
-Expression     ::= INDENT Identifier ":" "|\n"? PyRightHandExpression Comment? "\n" DEDENT
-DoAction       ::= INDENT Identifier ":" Comment? "\n" Action DEDENT
-Action         ::= INDENT "action:" PyExpression Comment? "\n" DEDENT
+Shape          ::= Libraries | Expression | DoAction | SketchObject
+Libraries      ::= INDENT "libraries:" " " (PyImport | "[" (PyImport ",")+ PyImport "]") "\n" DEDENT
+Expression     ::= INDENT Identifier ":" " " "|\n"? PyRightHandExpression Comment? "\n" DEDENT
+DoAction       ::= INDENT Identifier ":" " " Comment? "\n" Action DEDENT
+Action         ::= INDENT "action:" " " PyExpression Comment? "\n" DEDENT
 SketchObject   ::= INDENT Formula Styles? Transforms? DEDENT
-Formula        ::= INDENT "|\n"? SketcherCreator Comment? "\n" DEDENT
+Formula        ::= INDENT "formula:" (" " | "|\n") SketcherCreator Comment? "\n" DEDENT
 SketcherCreator::= SketcherClass "(" PyFunctionArgs ")"
 SketcherClass  ::= "Line" | "Rectangle" | "Triangle" | "Circle" | "Distance_wText" | "Text" | "Cross" | "Axis" |
 "Arc" | "Arc_wText" | "Arrow1" | "Force" | "Wall" | "Curve" | "Trajectory" | "Gravity" | "Moment" | "Text_wArrow" | "Wheel" | "Spring" | "Dashpot"