Splitting Part 1 and Part 2 in TOC

Arthur suggested to me that it would be good to have a more visible 
separation between

     Introduction
     Section 2 - 6 (Core)
     Section 7 onwards (Advanced)

I wish I could separate the Table of Contents so that it looked like

  * 1.Introduction <http://w3c.github.io/data-shapes/shacl/#introduction>
      o 1.1Document Outline
        <http://w3c.github.io/data-shapes/shacl/#introduction-outline>
      o 1.2Overview and Terminology of Core Features
        <http://w3c.github.io/data-shapes/shacl/#introduction-overview>
      o 1.3Overview and Terminology of Advanced Features
        <http://w3c.github.io/data-shapes/shacl/#introduction-overview-advanced>
      o 1.4Namespaces <http://w3c.github.io/data-shapes/shacl/#namespaces>

    *PART 1: **SHACL Core Profile**
    *

  * 2.Shapes <http://w3c.github.io/data-shapes/shacl/#shapes>
      o 2.1Shape Labels and Comments
        <http://w3c.github.io/data-shapes/shacl/#shape-labels>
      o 2.2Shape Specialization Mechanism
        <http://w3c.github.io/data-shapes/shacl/#shape-specialization>
      o 2.3Shape Constraints
        <http://w3c.github.io/data-shapes/shacl/#shape-constraints>
  * 3.Property Constraints
    <http://w3c.github.io/data-shapes/shacl/#property-constraints>
      o 3.1Property Constraints (sh:property)
        <http://w3c.github.io/data-shapes/shacl/#property-constraints-property>

          + 3.1.1sh:allowedValues
            <http://w3c.github.io/data-shapes/shacl/#AbstractAllowedValuesPropertyConstraint>
          + 3.1.2sh:datatype
            <http://w3c.github.io/data-shapes/shacl/#AbstractDatatypePropertyConstraint>
          + 3.1.3sh:hasValue
            <http://w3c.github.io/data-shapes/shacl/#AbstractHasValuePropertyConstraint>
          + 3.1.4sh:minCount, sh:maxCount
            <http://w3c.github.io/data-shapes/shacl/#AbstractCountPropertyConstraint>
          + 3.1.5sh:nodeKind
            <http://w3c.github.io/data-shapes/shacl/#AbstractNodeKindPropertyConstraint>
          + 3.1.6sh:valueShape
            <http://w3c.github.io/data-shapes/shacl/#AbstractValueShapePropertyConstraint>
          + 3.1.7sh:valueType
            <http://w3c.github.io/data-shapes/shacl/#AbstractValueTypePropertyConstraint>
      o 3.2Inverse Property Constraints (sh:inverseProperty)
        <http://w3c.github.io/data-shapes/shacl/#property-constraints-inverseProperty>
  * 4.Disjunctive Constraints (sh:OrConstraint)
    <http://w3c.github.io/data-shapes/shacl/#or>
  * 5.Scope of Constraints (sh:scope)
    <http://w3c.github.io/data-shapes/shacl/#scope>
  * 6.Constraint Violations Vocabulary
    <http://w3c.github.io/data-shapes/shacl/#violations>
      o 6.1Types of Constraint Violations
        <http://w3c.github.io/data-shapes/shacl/#violations-types>
      o 6.2Structural Violation Metadata
        <http://w3c.github.io/data-shapes/shacl/#violations-structure>
          + 6.2.1sh:root
            <http://w3c.github.io/data-shapes/shacl/#violations-structure-root>
          + 6.2.2sh:path
            <http://w3c.github.io/data-shapes/shacl/#violations-structure-path>
          + 6.2.3sh:value
            <http://w3c.github.io/data-shapes/shacl/#violations-structure-value>
          + 6.2.4sh:source
            <http://w3c.github.io/data-shapes/shacl/#violations-structure-source>
          + 6.2.5sh:detail
            <http://w3c.github.io/data-shapes/shacl/#violations-structure-detail>
      o 6.3Human-readable Violation Messages (sh:message)
        <http://w3c.github.io/data-shapes/shacl/#violations-message>
  *

    *PART 2: Advanced Topics**
    *

    **7.General Shape Constraints (sh:constraint)
    <http://w3c.github.io/data-shapes/shacl/#general-constraints>
  * ...

I do not believe ReSpec allows me to do that (does anyone know?), but 
I'd be happy to manually inject such intermediate headers into the final 
HTML before publication. It would also make it easier for us to state 
that we expect feedback on Part 1 as part of the FPWD while we could 
leave Part 2 as "informative" and unstable if we cannot agree on this in 
time of publication.

Thanks,
Holger