docs/conf.py: Include the content of prerelease.txt in the version string

Author: cameel

docs/conf.py

@@ -128,8 +128,10 @@ def get_github_username_repo(url):
 # The full version, including alpha/beta/rc tags.
 if os.path.isfile('../prerelease.txt') and os.path.getsize('../prerelease.txt') == 0:
     release = version
+elif os.path.isfile('../prerelease.txt'):
+    with open('../prerelease.txt', 'r', encoding='utf8') as prerelease_file:
+        release = version + '-' + prerelease_file.read()
 else:
-    # This is a prerelease version
     release = version + '-develop'
 
 # The language for content autogenerated by Sphinx. Refer to documentation