feat: Support job cancellation for QPUs, perform automatic retries on transient network failures.

docs/source/the_quantum_computer.rst

@@ -277,6 +277,29 @@ want a script that works for both QVM and QPU targets, you could do the followin
         # Working with a QPU - refresh calibrations
         qc.compiler.get_calibration_program(force_refresh=True)
 
+Requesting a job cancellation
+-----------------------------
+
+Jobs submitted to a QPU are queued for execution before they are run. While a job is pending execution, you can request
+that the job be cancelled with `:py:meth:~pyquil.api.QPU#cancel`. This functionality is unavailable on the QVM, so you
+can use a similar strategy to above to make sure the Quantum Abstract Machine (QAM) backing the QuantumComputer is
+indeed a QPU to safely call this method:
+
+.. code:: python
+
+    from pyquil.api import QPU
+
+   job_handle = qc.qam.execute(p)
+
+   if isinstance(qc.qam, QPU):
+        try:
+            qc.qam.cancel(job_handle)
+            print("Job was cancelled")
+        except QpuApiError:
+            # If this error was raised, then the job failed to be cancelled.
+            result = qc.qam.get_result(job_handle)
+
+
 Providing your own quantum processor topology
 =============================================