message: Change documentation to reflect that HLO stands for high-level operations
diff: @@ -35,9 +35,9 @@ We had several objectives for XLA to work with TensorFlow:
  ## How does XLA work?
  The input language to XLA is called "HLO IR", or just HLO (High Level
  -Optimizer). The semantics of HLO are described on the
  -[Operation Semantics](./operation_semantics.md) page. It
  -is most convenient to think of HLO as a
  +Operations). The semantics of HLO are described on the
  +[Operation Semantics](./operation_semantics.md) page. It is most convenient to
  +think of HLO as a
  [compiler IR](https://en.wikipedia.org/wiki/Intermediate_representation).
  XLA takes graphs ("computations") defined in HLO and compiles them into machine
  