Post template for myself

This is for myself:

• Title case for tags & category
• lower case for filename
• Add intro for every post for meta preview section. (first 50 words)
• backup chinese version before replace for config files due to some may override the langauge setting
• For the file that applies to both langauge version e.g. the Jekyll customerisation, markdown cheatsheet post & this file, just maintain one since it is easy to modify file the wrong file with the same name.
• Header image - resizer, since header image will be strech, it’s either crop the middle section to maintain aspect ratio or manually tune the size (900 * 400 is ok)

TODO:

• Add collapsible for long code snippet.