Release notes for 1.8.0 (#923)

* release notes for 1.8.0

release_notes.md

@@ -1,3 +1,35 @@
+*******************************
+# Release Notes for Dymos 1.8.0
+
+April 18, 2023
+
+Dymos 1.8.0 removes some deprecated OpenMDAO features that are removed as of version 3.26.0.
+It also adds a new trajectory results report that is generated by `dymos.run_problem(..., make_plots=True)`.
+This single HTML file contains summaries of the parameters in each phase as well as plots of the timeseries values
+across phases in each trajectory.
+Generating this file requires `bokeh` rather than matplotlib - a message in the HTML file will inform the user if bokeh
+was unavailable.
+ExplicitShooting is now consistent with `solve_segments` in the way initial state values are specified.
+This release also provides better logic when connecting variables of different units via phase linkages.
+
+## Backwards Incompatible API Changes & Deprecations
+- Remove deprecated src_indices argument in add_parameter() [#920](https://github.com/OpenMDAO/dymos/pull/920)
+- Initial states in ExplicitShooting now provided with `phase_path.initial_states:state_name` [#915](https://github.com/OpenMDAO/dymos/pull/915)
+
+## Enhancements
+- trajectory results report now automatically generated by run_problem [#918](https://github.com/OpenMDAO/dymos/pull/918)
+
+## Bug Fixes
+- Added better logic to detect different units across linkage constraints. [#913](https://github.com/OpenMDAO/dymos/pull/913)
+
+## Miscellaneous
+- Documentation fixes [#906](https://github.com/OpenMDAO/dymos/pull/906)
+- Cleaned up GitHub workflows [#907](https://github.com/OpenMDAO/dymos/pull/907)
+- Minor changes focused on plotting utility [#908](https://github.com/OpenMDAO/dymos/pull/908)
+- Documentation fixes [#909](https://github.com/OpenMDAO/dymos/pull/909)
+- Replaced deprecated 'value' keyword with 'val' [#910](https://github.com/OpenMDAO/dymos/pull/910)
+- Fixed missing component in Re-entry docs [#914](https://github.com/OpenMDAO/dymos/pull/914)
+
 *******************************
 # Release Notes for Dymos 1.7.0