docs: Expand and clarify usage of the history prune command (#3084)

Added a bit of context to make it clearer how this command works and
when one might want to use it.

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1 files changed, 4 insertions, 0 deletions

diff --git a/docs/docs/reference/prune.md b/docs/docs/reference/prune.md
index 5d85819a..40a75d5c 100644
--- a/docs/docs/reference/prune.md
+++ b/docs/docs/reference/prune.md
@@ -4,6 +4,10 @@
 
 This command deletes history entries matching the [history_filter](../configuration/config.md#history_filter) configuration parameter.
 
+These may be commands that match the current `history_filter` configuration, but were saved to history before the filter was set up, and therefore were not excluded from history at the time of execution.
+
+It may be useful to run the prune command after updating `history_filter` to remove old history entries that match the new filters.
+
 It can be run with `--dry-run` first to list history entries that will be removed.
 
 | Argument         | Description                                                        |