doc: clarify behavior of --preserve-env option in README and main.rs

Author: LeChatP

book/src/sr/README.md

@@ -14,7 +14,7 @@
   <b>-r, --role</b> &lt;ROLE&gt;  Role to select
   <b>-t, --task</b> &lt;TASK&gt;  Task to select (--role required)
   <b>-u, --user</b> &lt;USER&gt;  Specify the user to execute the command as
-  <b>-E, --preserve-env</b>  Preserve environment variables
+  <b>-E, --preserve-env</b>  Preserve environment variables if allowed by a matching task
   <b>-p, --prompt</b> &lt;PROMPT&gt; Prompt to display
   <b>-i, --info</b>         Display rights of executor
   <b>-h, --help</b>         Print help (see more with '--help')

src/sr/main.rs

@@ -60,7 +60,7 @@ const USAGE: &str = formatcp!(
           Task option allows you to select a specific task to use in the selected role. Note: You must specify a role to designate a task
 
   {BOLD}-E, --preserve-env <TASK>{RST}
-          Task option allows you to select a specific task to use in the selected role. Note: You must specify a role to designate a task
+          Preserve environment variables if allowed by a matching task
 
   {BOLD}-p, --prompt <PROMPT>{RST}
           Prompt option allows you to override the default password prompt and use a custom one