docs: Reference conntrack metrics in troubleshooting guide

The troubleshooting guide explains packet drops seen due to
conntrack map fill-up issue. Reference some of the conntrack
garbage collection related metrics so that users get visibility
into conntrack gc runs - how often it's being triggered, how many
entries were gc'd, etc.

Signed-off-by: Aditi Ghag <aditi@cilium.io>

Documentation/operations/troubleshooting.rst

@@ -404,7 +404,10 @@ default. The default starting interval is 5 minutes. Alternatively, the value
 for ``bpf-ct-global-any-max`` and ``bpf-ct-global-tcp-max`` can be increased.
 Setting both of these options will be a trade-off of CPU for ``conntrack-gc-interval``, and for
 ``bpf-ct-global-any-max`` and ``bpf-ct-global-tcp-max`` the amount of memory
-consumed.
+consumed. You can track conntrack garbage collection related metrics such as
+``datapath_conntrack_gc_runs_total`` and ``datapath_conntrack_gc_entries`` to
+get visibility into garbage collection runs. Refer to :ref:`metrics` for more
+details.
 
 Enabling datapath debug messages
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~