cmd/testscript: document -work flag in help and README (#123)

Author: myitcv

cmd/testscript/README.md

@@ -3,7 +3,7 @@ The testscript command runs github.com/rogpeppe/go-internal/testscript scripts
 in a fresh temporary work directory tree.
 
 Usage:
-    testscript [-v] [-e VAR[=value]]... [-u] files...
+    testscript [-v] [-e VAR[=value]]... [-u] [-work] files...
 
 The testscript command is designed to make it easy to create self-contained
 reproductions of command sequences.
@@ -31,6 +31,9 @@ succeed and the testscript file will be updated to reflect the actual content.
 As such, this is the cmd/testcript equivalent of
 testscript.Params.UpdateScripts.
 
+The -work flag prints the temporary work directory path before running each
+script, and does not remove that directory when testscript exits.
+
 Examples
 ========
 

cmd/testscript/help.go

@@ -14,7 +14,7 @@ The testscript command runs github.com/rogpeppe/go-internal/testscript scripts
 in a fresh temporary work directory tree.
 
 Usage:
-    testscript [-v] [-e VAR[=value]]... [-u] files...
+    testscript [-v] [-e VAR[=value]]... [-u] [-work] files...
 
 The testscript command is designed to make it easy to create self-contained
 reproductions of command sequences.
@@ -42,6 +42,9 @@ succeed and the testscript file will be updated to reflect the actual content.
 As such, this is the cmd/testcript equivalent of
 testscript.Params.UpdateScripts.
 
+The -work flag prints the temporary work directory path before running each
+script, and does not remove that directory when testscript exits.
+
 Examples
 ========