Better restarts of eg25-manager and qmi-wwan-manager

src/operation/scripting.md

@@ -182,6 +182,7 @@ facet terminates, *Instruction* is run.
     `dataspace` |  
     `timestamp` |  
     `facet` |  
+    `stringify` *ConvenienceExpr* |  
     *ValueExpr*
 
 Values can be destructured and new variables introduced into the environment with `let`, which
@@ -202,6 +203,9 @@ the following special "convenience" expressions:
    `stop` to the entity (using e.g. the *SendInstruction* "`! stop`") triggers termination of
    its associated facet. The entity does not respond to any other assertion or message.
 
+ - `stringify`: Evaluates its argument, then renders it as a Preserves value using Preserves
+   text syntax, and yields the resulting string.
+
 ### Conditional execution
 
 *ConditionalInstruction* = `$`*var*` =~ `*PatternExpr*` `*Instruction*` `*Instruction* ...