f-string docs update: the level of expression nesting in format specifiers

PEP 701 said:

Similarly, this PEP leaves up to the implementation the level of expression nesting in format specifiers but specifies a lower bound of 2 levels of nesting. This means that the following should always be valid:
f"{'':*^{1:{1}}}"

However, the docs haven't updated:

BTW, IIUC the specification of f-string has moved from syntax(lexical) to grammar.
Thus, it probably should be moved from https://docs.python.org/3.12/reference/lexical_analysis.html#formatted-string-literals to https://docs.python.org/3.12/reference/grammar.html or https://docs.python.org/3.12/reference/expressions.html#literals. Or a special note should be added.
At least this lexical grammar is outdated and should be removed (or replaced by the PEG grammar):

首先，將 PEP 701 與 docs.python.org/3.12/reference/lexical_analysis.html 中關於格式化字串常值的章節，以及其中參照的文法和運算式章節進行比較。更新文件，說明支援的運算式巢狀層級，並釐清應刪除、取代過時的詞法文法，還是為其附加註記。