docs: add Sprig library functions to help topics

pkg/cmd/root/help_topic.go

@@ -151,6 +151,13 @@ var HelpTopics = []helpTopic{
 			- %[1]struncate <length> <input>%[1]s: ensures input fits within length
 			- %[1]shyperlink <url> <text>%[1]s: renders a terminal hyperlink
 
+			The following Sprig template library functions can also be used with this formatting directive:
+			- %[1]scontains%[1]s: returns true if the input contains the argument
+			- %[1]shasPrefix%[1]s: returns true if the input has the argument as a prefix
+			- %[1]shasSuffix%[1]s: returns true if the input has the argument as a suffix
+			- %[1]sregexMatch%[1]s:	returns true if the input matches the argument
+			For more information about the Sprig library, see <https://masterminds.github.io/sprig/>.
+
 			To learn more about Go templates, see: <https://golang.org/pkg/text/template/>.
 		`, "`"),
 		example: heredoc.Doc(`