[FEATURE]Sync top README with index.rts about supported grammer

[gaodi16366]

Grammar or Syntax Description

• https://github.com/JSQLParser/JSqlParser/blob/0f9e477944332c4711b4056984e7d383f15c9237/src/site/sphinx/index.rst?plain=1#L86C1-L98C1 is inconsistent with https://github.com/JSQLParser/JSqlParser/blob/0f9e477944332c4711b4056984e7d383f15c9237/README.md?plain=1#L86C1-L95C1
• I'm just confused that if JSQLParser support Snowflake or not.

SQL Example

• None

Additional context

Tips:

[manticore-projects]

Greetings!

Snowflake is supported to a very large extend.
If you find anything missing you are welcome to file a feature request.

Cheers!