Update ReadTheDocs configuration for Python version and build process

- Upgraded Python version from 3.9 to 3.12 in the build configuration.
- Streamlined the installation of Python requirements by referencing `docs/requirements.txt`.
- Enhanced multilingual support with a pre-build job for creating language indices.
- Cleaned up comments and structure for clarity in the configuration file.

Author: adamzhang1987

.readthedocs.yaml

@@ -1,41 +1,36 @@
 # .readthedocs.yaml
-# Read the Docs configuration file
-# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
-
-# Required
 version: 2
 
-# Set the version of Python and other tools you might need
+# Set the OS, Python version and other tools
 build:
   os: ubuntu-22.04
   tools:
-    python: "3.9"
-    # You can also specify other tool versions:
-    # nodejs: "16"
-    # rust: "1.55"
-    # golang: "1.17"
+    python: "3.12"
 
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
-   configuration: docs/source/conf.py
+  configuration: docs/source/conf.py
 
-# If using Sphinx, optionally build your docs in additional formats such as PDF
+# Optionally build your docs in additional formats
 formats:
   - pdf
-  - epub
 
 # Optionally declare the Python requirements required to build your docs
 python:
-   install:
-     - method: pip
-       path: .
-       extra_requirements:
-         - docs
+  install:
+    - requirements: docs/requirements.txt
+
+# Multilingual configuration
+sphinx:
+  configuration: docs/source/conf.py
+  fail_on_warning: false
 
-languages:
-  en:
-    name: English
-    version: latest
-  zh_CN:
-    name: 中文
-    version: latest
+# MultiLanguage documentation with subdirectories approach
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.12"
+  jobs:
+    pre_build:
+      # Create the language-specific indices
+      - echo "Creating language indices..."