docs: floordiv (#3797)

add docs for floordiv

* add note on rounding for negative integers

---------

Co-authored-by: Charles Cooper <cooper.charles.m@gmail.com>

docs/types.rst

@@ -95,7 +95,7 @@ Operator       Description
 ``x - y``      Subtraction
 ``-x``         Unary minus/Negation
 ``x * y``      Multiplication
-``x / y``      Division
+``x // y``     Integer division
 ``x**y``       Exponentiation
 ``x % y``      Modulo
 =============  ======================
@@ -131,6 +131,8 @@ Shifting is only available for 256-bit wide types. That is, ``x`` must be ``int2
 .. note::
    While at runtime shifts are unchecked (that is, they can be for any number of bits), to prevent common mistakes, the compiler is stricter at compile-time and will prevent out of bounds shifts. For instance, at runtime, ``1 << 257`` will evaluate to ``0``, while that expression at compile-time will raise an ``OverflowException``.
 
+.. note::
+   Integer division has different rounding semantics than Python for negative numbers: Vyper rounds towards zero, while Python rounds towards negative infinity. For example, ``-1 // 2` will return ``-1`` in Python, but ``0`` in Vyper.
 
 .. index:: ! uint, ! uintN, ! unsigned integer
 
@@ -181,7 +183,7 @@ Operator                     Description
 ``x + y``                    Addition
 ``x - y``                    Subtraction
 ``x * y``                    Multiplication
-``x / y``                    Division
+``x // y``                   Integer division
 ``x**y``                     Exponentiation
 ``x % y``                    Modulo
 ===========================  ======================
@@ -270,7 +272,7 @@ Operator       Description
 ``x - y``      Subtraction
 ``-x``         Unary minus/Negation
 ``x * y``      Multiplication
-``x / y``      Division
+``x / y``      Decimal division
 ``x % y``      Modulo
 =============  ==========================================