DOCS/man/input.rst: document the scalable commands

This documents the commands which are scalable, and refer
to information on how it affects input processing.

DOCS/man/input.rst

@@ -295,6 +295,9 @@ Remember to quote string arguments in input.conf (see `Flat command syntax`_).
     3rd parameter (essentially using a space instead of ``+``). The 3rd
     parameter is still parsed, but is considered deprecated.
 
+    This is a scalable command. See the documentation of ``nonscalable`` input
+    prefix in `Input Command Prefixes`_ for details.
+
 ``revert-seek [<flags>]``
     Undoes the ``seek`` command, and some other commands that seek (but not
     necessarily all of them). Calling this command once will jump to the
@@ -341,6 +344,9 @@ Remember to quote string arguments in input.conf (see `Flat command syntax`_).
     Add the given value to the property or option. On overflow or underflow,
     clamp the property to the maximum. If ``<value>`` is omitted, assume ``1``.
 
+    This is a scalable command. See the documentation of ``nonscalable`` input
+    prefix in `Input Command Prefixes`_ for details.
+
 ``cycle <name> [<value>]``
     Cycle the given property or option. The second argument can be ``up`` or
     ``down`` to set the cycle direction. On overflow, set the property back to
@@ -351,6 +357,9 @@ Remember to quote string arguments in input.conf (see `Flat command syntax`_).
     Currently properties with continuous values are repeatable by default (like
     ``volume``), while discrete values are not (like ``osd-level``).
 
+    This is a scalable command. See the documentation of ``nonscalable`` input
+    prefix in `Input Command Prefixes`_ for details.
+
 ``multiply <name> <value>``
     Similar to ``add``, but multiplies the property or option with the numeric
     value.
@@ -1357,6 +1366,9 @@ Remember to quote string arguments in input.conf (see `Flat command syntax`_).
     Future versions can add more arguments and more key state characters to
     support more input peculiarities.
 
+    This is a scalable command. See the documentation of ``nonscalable`` input
+    prefix in `Input Command Prefixes`_ for details.
+
 ``ab-loop``
     Cycle through A-B loop states. The first command will set the ``A`` point
     (the ``ab-loop-a`` property); the second the ``B`` point, and the third