[Style Guide] Apply uniform title and subtitle styles to all lectures

[mmcky]

According to our style guide, every subtitle should only capitalize the first letter which is not the case in the following lectures

The following series needs to be reviewed and updated

• lecture-python-programming
• lecture-python-intro
• lecture-python.myst [Intermediate Lecture Series] Fix Title Style lecture-python.myst#512
• lecture-python-advanced.myst [Advanced Lecture Series] Fix Title Style lecture-python-advanced.myst#237
• lecture-jax
• continuous_time_mc

thanks @llongye-tian for raising the detailed issues in each repository. It's super helpful 👍

[jstac]

Thanks @mmcky , it will be nice to get this done. I think you can cut the words "in intermediate series" from the first line.