Qiskit-sphinx-theme

Search box fix

* Add Segment to the qiskit documentation page 60
* Add unified top menu bar to layout.html 64
* Remove unnecessary code from layout file
* Fix `blockquote` css 103

* Fixing analytics.

* Fix some typos before the release.

* Add Segment to the qiskit documentation page 60
* Add unified top menu bar to layout.html 64
* Remove unnecessary code from layout file
* Fix blockquote css 103

* Introduced deprecation note style (https://github.com/Qiskit/qiskit_sphinx_theme/pull/73)
* Synchronised theme templates from upstream (https://github.com/Qiskit/qiskit_sphinx_theme/pull/49)