feature #11802 [Process] allow writing "prepared" command line. (Simperfit)

This PR was submitted for the master branch but it was merged into the 4.4 branch instead (closes #11802).

Discussion
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[Process] allow writing "prepared" command line.

This documents the re-pushed prepared command line with a new style of writing it that does not break anything.

symfony/symfony#32126

Commits
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05f8941 [Process] allow writing "prepared" command line.

Author: OskarStark

components/process.rst

@@ -350,6 +350,19 @@ instead::
     );
     $process->run();
 
+Using a Prepared Command Line
+--------------------------------
+
+This component also provides a way to use the process command with prepared using the double brackets notations:
+Which means that you can use placeholder in order to have a process that can be changed only with the values and without changing the php code.
+The component will not escape the characters, you are responsible of doing so::
+
+  use Symfony\Component\Process\Process;
+
+  $process = Process::fromShellCommandline('echo "$name"');
+  $process->run(null, ['name' => 'elsa']);
+
+
 Process Timeout
 ---------------