message: docs: clarify the shortcomings of local variable technique for parent-child component interactions
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diff: @@ -300,8 +300,11 @@ The *local variable* approach is easy. But it is limited because
  the parent-child wiring must be done entirely within the parent template.
  The parent component *itself* has no access to the child.
  -You can't use the *local variable* technique if an instance of the parent component *class*
  -must read or write child component values or must call child component methods.
  +You can't use the *local variable* technique if the parent component's *class* relies on the
  +child component's *class*. The parent-child relationship of the components is not established
  +within each components respective *class* with the *local variable* technique. Since the *class*
  +instances are not connected to one another, the parent *class* cannot access the child *class*
  +properties and methods.
  When the parent component *class* requires that kind of access,
  ***inject*** the child component into the parent as a *ViewChild*.
  