[container.node] Remove placeholder class name from subheadings.

Partially addresses #1242.

Author: zygoloid

source/containers.tex

@@ -1199,10 +1199,10 @@
 
 \rSec2[container.node]{Node handles}
 
-\rSec3[container.node.overview]{\tcode{node_handle} overview}
+\rSec3[container.node.overview]{Overview}
 
 \pnum
-A \term{node handle} is an object that accepts ownership of a single element
+A \defn{node handle} is an object that accepts ownership of a single element
 from an associative container\iref{associative.reqmts} or an unordered
 associative container\iref{unord.req}. It may be used to transfer that
 ownership to another container with compatible nodes.  Containers with
@@ -1249,46 +1249,51 @@
 
 \begin{codeblock}
 template<@\unspecnc@>
-  class @\placeholder{node_handle}@ {
-  public:
-    // These type declarations are described in Tables \ref{tab:containers.associative.requirements} and \ref{tab:HashRequirements}.
-    using value_type     = @\seebelownc{}@;   // not present for map containers
-    using key_type       = @\seebelownc{}@;   // not present for set containers
-    using mapped_type    = @\seebelownc{}@;   // not present for set containers
-    using allocator_type = @\seebelownc{}@;
-
-  private:
-    using container_node_type = @\unspecnc@;
-    using ator_traits = allocator_traits<allocator_type>;
-
-    typename ator_traits::rebind_traits<container_node_type>::pointer ptr_;
-    optional<allocator_type> alloc_;
-
-  public:
-    constexpr @\placeholdernc{node_handle}@() noexcept : ptr_(), alloc_() {}
-    ~@\placeholdernc{node_handle}@();
-    @\placeholdernc{node_handle}@(@\placeholdernc{node_handle}@&&) noexcept;
-    @\placeholdernc{node_handle}@& operator=(@\placeholdernc{node_handle}@&&);
-
-    value_type& value() const;          // not present for map containers
-    key_type& key() const;              // not present for set containers
-    mapped_type& mapped() const;        // not present for set containers
-
-    allocator_type get_allocator() const;
-    explicit operator bool() const noexcept;
-    [[nodiscard]] bool empty() const noexcept;
-
-    void swap(@\placeholdernc{node_handle}@&)
-      noexcept(ator_traits::propagate_on_container_swap::value ||
-               ator_traits::is_always_equal::value);
-
-    friend void swap(@\placeholdernc{node_handle}@& x, @\placeholdernc{node_handle}@& y) noexcept(noexcept(x.swap(y))) {
-      x.swap(y);
-    }
+class @\placeholder{node_handle}@ {
+public:
+  // These type declarations are described in Tables \ref{tab:containers.associative.requirements} and \ref{tab:HashRequirements}.
+  using value_type     = @\seebelownc{}@;     // not present for map containers
+  using key_type       = @\seebelownc{}@;     // not present for set containers
+  using mapped_type    = @\seebelownc{}@;     // not present for set containers
+  using allocator_type = @\seebelownc{}@;
+
+private:
+  using container_node_type = @\unspecnc@;
+  using ator_traits = allocator_traits<allocator_type>;
+
+  typename ator_traits::rebind_traits<container_node_type>::pointer ptr_;
+  optional<allocator_type> alloc_;
+
+public:
+  // \ref{container.node.cons}, constructors, copy, and assignment
+  constexpr @\placeholdernc{node_handle}@() noexcept : ptr_(), alloc_() {}
+  @\placeholdernc{node_handle}@(@\placeholdernc{node_handle}@&&) noexcept;
+  @\placeholdernc{node_handle}@& operator=(@\placeholdernc{node_handle}@&&);
+
+  // \ref{container.node.dtor}, destructor
+  ~@\placeholdernc{node_handle}@();
+
+  // \ref{container.node.observers}, observers
+  value_type& value() const;            // not present for map containers
+  key_type& key() const;                // not present for set containers
+  mapped_type& mapped() const;          // not present for set containers
+
+  allocator_type get_allocator() const;
+  explicit operator bool() const noexcept;
+  [[nodiscard]] bool empty() const noexcept;
+
+  // \ref{container.node.modifiers}, modifiers
+  void swap(@\placeholdernc{node_handle}@&)
+    noexcept(ator_traits::propagate_on_container_swap::value ||
+             ator_traits::is_always_equal::value);
+
+  friend void swap(@\placeholdernc{node_handle}@& x, @\placeholdernc{node_handle}@& y) noexcept(noexcept(x.swap(y))) {
+    x.swap(y);
+  }
 };
 \end{codeblock}
 
-\rSec3[container.node.cons]{\tcode{\placeholder{node_handle}} constructors, copy, and assignment}
+\rSec3[container.node.cons]{Constructors, copy, and assignment}
 
 \begin{itemdecl}
 @\placeholdernc{node_handle}@(@\placeholdernc{node_handle}@&& nh) noexcept;
@@ -1336,7 +1341,7 @@
 \pnum \throws Nothing.
 \end{itemdescr}
 
-\rSec3[container.node.dtor]{\tcode{\placeholder{node_handle}} destructor}
+\rSec3[container.node.dtor]{Destructor}
 
 \begin{itemdecl}
 ~@\placeholdernc{node_handle}@();
@@ -1350,7 +1355,7 @@
 \tcode{ator_traits::rebind_traits<container_node_type>::deallocate}.
 \end{itemdescr}
 
-\rSec3[container.node.observers]{\tcode{\placeholder{node_handle}} observers}
+\rSec3[container.node.observers]{Observers}
 
 \begin{itemdecl}
 value_type& value() const;
@@ -1439,7 +1444,7 @@
 \returns \tcode{ptr_ == nullptr}.
 \end{itemdescr}
 
-\rSec3[container.node.modifiers]{\tcode{\placeholder{node_handle}} modifiers}
+\rSec3[container.node.modifiers]{Modifiers}
 
 \begin{itemdecl}
 void swap(@\placeholdernc{node_handle}@& nh)