Update --help text for cache-related parameters (dbt-labs#7389)

Author: jtcohen6

.changes/unreleased/Under the Hood-20230418-122323.yaml

@@ -0,0 +1,6 @@
+kind: Under the Hood
+body: Update --help text for cache-related parameters
+time: 2023-04-18T12:23:23.276693+02:00
+custom:
+  Author: jtcohen6
+  Issue: "7381"

core/dbt/cli/params.py

@@ -23,7 +23,7 @@
 cache_selected_only = click.option(
     "--cache-selected-only/--no-cache-selected-only",
     envvar="DBT_CACHE_SELECTED_ONLY",
-    help="Pre cache database objects relevant to selected resource only.",
+    help="At start of run, populate relational cache only for schemas containing selected nodes, or for all schemas of interest.",
 )
 
 introspect = click.option(
@@ -121,7 +121,7 @@
 
 log_cache_events = click.option(
     "--log-cache-events/--no-log-cache-events",
-    help="Enable verbose adapter cache logging.",
+    help="Enable verbose logging for relational cache events to help when debugging.",
     envvar="DBT_LOG_CACHE_EVENTS",
 )
 
@@ -242,7 +242,7 @@
 populate_cache = click.option(
     "--populate-cache/--no-populate-cache",
     envvar="DBT_POPULATE_CACHE",
-    help="Allow for partial parsing by looking for and writing to a pickle file in the target directory. This overrides the user configuration file.",
+    help="At start of run, use `show` or `information_schema` queries to populate a relational cache, which can speed up subsequent materializations.",
     default=True,
 )