Add DUK_USE_GET_MONOTONIC_TIME config option

config/config-options/DUK_USE_DATE_GET_NOW.yaml

@@ -6,3 +6,7 @@ tags:
   - portability
 description: >
   Mandatory macro for getting the current time, see datetime.rst.
+
+  If the time provided experiences time jumps or doesn't advance in realtime
+  (which is useful in some time virtualization scenarios), consider defining
+  DUK_USE_GET_MONOTONIC_TIME.

config/config-options/DUK_USE_GET_MONOTONIC_TIME.yaml

@@ -0,0 +1,21 @@
+define: DUK_USE_GET_MONOTONIC_TIME
+introduced: 2.2.0
+default: false
+tags:
+  - date
+  - portability
+description: >
+  Optional macro for getting monotonic time starting from an arbitrary
+  starting point (device startup, program startup, script startup, etc).
+  The time returned must increase monotonically, and must not jump
+  discontinuously even if system date/time is reset.  The semantics are
+  similar to POSIX clock_gettime() CLOCK_MONOTONIC.
+
+  Monotonic time is used by Duktape for its internal needs, such as rate
+  limiting debugger transport peek callbacks.  If this option is not provided,
+  Duktape falls back to using DUK_USE_DATE_GET_NOW() which is usually fine.
+
+  If DUK_USE_DATE_GET_NOW() experiences time jumps or doesn't run in realtime
+  (which may be useful for some time virtualization cases) it's recommended
+  to provide this config option so that internals which need a reliable
+  realtime rate have a reliable time basis.