Keep version in header, only show selector if LAMMPS_WEBSITE_BUILD is set

doc/utils/sphinx-config/_themes/lammps_theme/layout.html

@@ -138,6 +138,10 @@
             {% if READTHEDOCS and current_version %}
               {%- set nav_version = current_version %}
             {% endif %}
+            {% if nav_version %}
+              <div class="lammps_version">Version: <b>{{ nav_version }}</b></div>
+              <div class="lammps_release">git info: {{ release }}</div>
+            {% endif %}
           {% endif %}
 
           {% include "searchbox.html" %}

doc/utils/sphinx-config/conf.py.in

@@ -408,11 +408,13 @@ try:
 except NameError:
    html_context = dict()
 
-html_context['display_manual_versions'] = True
-html_context['current_version'] = version
+is_website_build = os.environ.get('LAMMPS_WEBSITE_BUILD', '0') != '0'
+
+html_context['display_manual_versions'] = is_website_build
+html_context['current_version'] = os.environ.get('LAMMPS_WEBSITE_BUILD', version)
 html_context['git_commit'] = git_commit
 html_context['versions'] = [
-  ('latest', 'https://docs.lammps.org/'),
-  ('8 Apr 2021', 'https://lammps.sandia.gov/doc/')
+  ('latest', 'https://docs.lammps.org/latest/'),
+  (version, 'https://docs.lammps.org/')
 ]
 html_context['downloads'] = [('PDF', 'Manual.pdf')]