docs: adjust punctuation characters for header

docs/examples/emulator/README.rst

-Emulator examples
-=================
+Emulator
+========
\ No newline at end of file

docs/examples/inference/README.rst

-inference Examples
-^^^^^^^^^^^^^^^^^^
+Inference
+=========
\ No newline at end of file

docs/examples/sampler/README.rst

-sampler Examples
-^^^^^^^^^^^^^^^^
+Sampler
+=======
\ No newline at end of file

docs/examples/sensitivity/README.rst

-sensitivity Examples
-^^^^^^^^^^^^^^^^^^^^
+Sensitivity
+===========
\ No newline at end of file

docs/examples/simulator/README.rst

-Simulator examples
-==================
+Simulator
+=========