docs: Update inline docs on action/upgrade.go (#7834)

* docs: Update inline docs on action/upgrade.go

Signed-off-by: Matt Butcher <matt.butcher@microsoft.com>

* clarify atomic and cleanup-on-fail

Signed-off-by: Matt Butcher <matt.butcher@microsoft.com>

* updated the post-render documentation on action.Upgrade

Signed-off-by: Matt Butcher <matt.butcher@microsoft.com>

pkg/action/upgrade.go

@@ -43,27 +43,57 @@ type Upgrade struct {
 
 	ChartPathOptions
 
+	// Install is a purely informative flag that indicates whether this upgrade was done in "install" mode.
+	//
+	// Applications may use this to determine whether this Upgrade operation was done as part of a
+	// pure upgrade (Upgrade.Install == false) or as part of an install-or-upgrade operation
+	// (Upgrade.Install == true).
+	//
+	// Setting this to `true` will NOT cause `Upgrade` to perform an install if the release does not exist.
+	// That process must be handled by creating an Install action directly. See cmd/upgrade.go for an
+	// example of how this flag is used.
 	Install bool
+	// Devel indicates that the operation is done in devel mode.
 	Devel bool
+	// Namespace is the namespace in which this operation should be performed.
 	Namespace string
-	// SkipCRDs skip installing CRDs when install flag is enabled during upgrade
+	// SkipCRDs skips installing CRDs when install flag is enabled during upgrade
 	SkipCRDs bool
+	// Timeout is the timeout for this operation
 	Timeout time.Duration
+	// Wait determines whether the wait operation should be performed after the upgrade is requested.
 	Wait bool
+	// DisableHooks disables hook processing if set to true.
 	DisableHooks bool
+	// DryRun controls whether the operation is prepared, but not executed.
+	// If `true`, the upgrade is prepared but not performed.
 	DryRun bool
+	// Force will, if set to `true`, ignore certain warnings and perform the upgrade anyway.
+	//
+	// This should be used with caution.
 	Force bool
+	// ResetValues will reset the values to the chart's built-ins rather than merging with existing.
 	ResetValues bool
+	// ReuseValues will re-use the user's last supplied values.
 	ReuseValues bool
 	// Recreate will (if true) recreate pods after a rollback.
 	Recreate bool
 	// MaxHistory limits the maximum number of revisions saved per release
 	MaxHistory int
+	// Atomic, if true, will roll back on failure.
 	Atomic bool
+	// CleanupOnFail will, if true, cause the upgrade to delete newly-created resources on a failed update.
 	CleanupOnFail bool
+	// SubNotes determines whether sub-notes are rendered in the chart.
 	SubNotes bool
+	// Description is the description of this operation
 	Description string
+	// PostRender is an optional post-renderer
+	//
+	// If this is non-nil, then after templates are rendered, they will be sent to the
+	// post renderer before sending to the Kuberntes API server.
 	PostRenderer postrender.PostRenderer
+	// DisableOpenAPIValidation controls whether OpenAPI validation is enforced.
 	DisableOpenAPIValidation bool
 }