Add documentation for relative datetime snappish

cmd/kosli/diffSnapshots.go

@@ -18,6 +18,8 @@ const diffSnapshotsDesc = diffSnapshotsDescShort + `
 Specify SNAPPISH_1 and SNAPPISH_2 by:  
 - environmentName~<N>  N'th behind the latest snapshot  
 - environmentName#<N>  snapshot number N  
+- environmentName@{YYYY-MM-DDTHH:MM:SS} snapshot at specific moment in time in UTC
+- environmentName@{<N>.<hours|days|weeks|months>.ago} snapshot at a relative time
 - environmentName      the latest snapshot`
 
 const diffSnapshotsExample = `
@@ -35,7 +37,12 @@ kosli diff snapshots envName1 envName2 \
 kosli diff snapshots envName1 envName2 \
 	--show-unchanged \
 	--api-token yourAPIToken \
-	--org orgName`
+	--org orgName
+
+# compare the snapshot from 2 weeks ago in an environment to the latest
+kosli diff snapshots envName@{2.weeks.ago} envName \
+--api-token yourAPIToken \
+--org orgName`
 
 type diffSnapshotsOptions struct {
 	output        string

cmd/kosli/getSnapshot.go

@@ -78,6 +78,7 @@ Specify SNAPPISH by:
 - environmentName~<N>  					N'th behind the latest snapshot
 - environmentName#<N>  					snapshot number N
 - environmentName@{YYYY-MM-DDTHH:MM:SS} snapshot at specific moment in time in UTC
+- environmentName@{<N>.<hours|days|weeks|months>.ago} snapshot at a relative time
 - environmentName      					the latest snapshot`
 
 const getSnapshotExample = `
@@ -96,10 +97,15 @@ kosli get snapshot yourEnvironmentName#23
 	--api-token yourAPIToken \
 	--org yourOrgName 
 	
-# get an environment snapshot at midday (UTC), on valentine's day of 2023:
+# get the environment snapshot at midday (UTC), on valentine's day of 2023:
 kosli get snapshot yourEnvironmentName@{2023-02-14T12:00:00}
 	--api-token yourAPIToken \
-	--org yourOrgName`
+	--org yourOrgName
+
+# get the environment snapshot based on a relative time:
+kosli get snapshot yourEnvironmentName@{3.weeks.ago}
+--api-token yourAPIToken \
+--org yourOrgName`
 
 func newGetSnapshotCmd(out io.Writer) *cobra.Command {
 	o := new(environmentGetOptions)