Doc: Py_EnterRecursiveCall uses C stack space, not a call counter

[BHUVANSH855]

Documentation

As of 3.14, Py_EnterRecursiveCall and Py_LeaveRecursiveCall no longer use
a call counter (c_recursion_remaining); they compare the current C stack
pointer against tstate->c_stack_soft_limit.

The documentation still describes the check as "if the stack limit is reached"
without clarifying that this is actual C stack consumption, unaffected by
sys.setrecursionlimit(). This was noted by @ZeroIntensity in
#156205 (review)

Linked PRs

• gh-158643: Doc: document that Py_EnterRecursiveCall uses C stack, not a counter #158644
• [3.15] gh-158643: Document that Py_EnterRecursiveCall uses the C stack, not a counter (GH-158644) #158653
• [3.14] gh-158643: Document that Py_EnterRecursiveCall uses the C stack, not a counter (GH-158644) #158654

[ZeroIntensity]

(For future reference, we usually don't need a new issue for documentation changes.)