sqlite3 docs: clarify transaction control for SELECT

[KennyChenBasis]

Documentation

In https://docs.python.org/3/library/sqlite3.html#transaction-control, it says that transactions are implicitly opened before INSERT, UPDATE, DELETE, or REPLACE statements, but it leaves open what happens for SELECT statements. Especially in the light of #54133, it should be more clear that SELECT statements don't start a transaction, either by saying "only" INSERT, etc. statements implicitly open transactions, or adding another sentence.

CC: @erlend-aasland @CAM-Gerlach

[CAM-Gerlach]

At least in my (beginner-level) reading of the docs, it seems implicit to me that a transaction is opened before these, and only these statements, i.e. in formal logic "If and only if a statement is a INSERT, UPDATE, DELETE or REPLACE statement, an SQL transaction is implicitly opened before that statement." But if there is concern that users might be uncertain if one is opened before SELECT, or we want to call attention to that fact (being the other member of the CRUD quartet), the the wording could be revised to add a parenthetical calling this out:

and executemany() executes INSERT, UPDATE, DELETE, or REPLACE (but not SELECT) statements.

@erlend-aasland ?

[erlend-aasland]

Sure, I see no reason not to be explicit. It'll also help reduce the number of issues like this.