message: docs(glossary): Add table of contents
diff: @@ -4,6 +4,43 @@ When discussing and documenting observables, it's important to have a common lan
  While not all of the documentation for RxJS reflects this terminology, it is a goal of the team to ensure it does, and to ensure the language and names around the library use this document as a source of truth and unified language.
  +- [RxJS: Glossary And Semantics](#rxjs-glossary-and-semantics)
  + - [Major Entities](#major-entities)
  + - [Consumer](#consumer)
  + - [Producer](#producer)
  + - [Subscription](#subscription)
  + - [Observable](#observable)
  + - [Observer](#observer)
  + - [Major Actions](#major-actions)
  + - [Subscribe](#subscribe)
  + - [Teardown](#teardown)
  + - [Unsubscription](#unsubscription)
  + - [Observation](#observation)
  + - [Observation Chain](#observation-chain)
  + - [Next](#next)
  + - [Error](#error)
  + - [Complete](#complete)
  + - [Notification](#notification)
  + - [Major Concepts](#major-concepts)
  + - [Multicast](#multicast)
  + - [Unicast](#unicast)
  + - [Cold](#cold)
  + - [Hot](#hot)
  + - [Minor Entities](#minor-entities)
  + - [Operator](#operator)
  + - [Operator Function](#operator-function)
  + - [Operation](#operation)
  + - [Stream](#stream)
  + - [Source](#source)
  + - [Observable Inputs](#observable-inputs)
  + - [Notifier](#notifier)
  + - [Inner Source](#inner-source)
  + - [Partial Observer](#partial-observer)
  + - [Other Concepts](#other-concepts)
  + - [Unhandled Errors](#unhandled-errors)
  + - [Producer Interference](#producer-interference)
  + - [Upstream And Downstream](#upstream-and-downstream)
  +
  ## Major Entities
  There are high level entities that are frequently discussed. It's important to define them seperately from other lower-level concepts, because they relate to the nature of observable.
  