Fix version information in doc selection (brucefan1983#438)

* Added parsing of version information when compiling documentation

* Changed "latest stable release" to "latest release"

* Cleaned up conf.py

* Keep "v" in version

Author: erhart1

doc/conf.py

@@ -5,13 +5,21 @@
 import sys
 import re
 import sphinx_rtd_theme
+import subprocess
 
 project = 'GPUMD'
 author = 'The GPUMD developer team'
-version = ''
 copyright = '2023'
 site_url = 'https://gpumd.org'
 
+process = subprocess.Popen(['git', 'tag'], stdout=subprocess.PIPE)
+stdout, _ = process.communicate()
+versions = [s for s in stdout.decode().split('\n') if len(s)]
+if len(versions) > 0:
+    version = versions[-1]
+else:
+    version = ''
+
 extensions = [
     'sphinx_sitemap',
     'sphinx.ext.autodoc',
@@ -47,7 +55,7 @@
 html_context = {
     'current_version': version,
     'versions':
-        [('latest stable release',
+        [('latest release',
           '{}'.format(site_url)),
          ('development version',
           '{}/dev'.format(site_url))]}