minor #8096 Add default indication in input arguments/options description (medinae, javiereguiluz)

This PR was submitted for the 3.3 branch but it was merged into the 2.7 branch instead (closes #8096).

Discussion
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Add default indication in input arguments/options description

As i had to check in the code to find the information (even if it can seems logical for some people), i think it can be good to precise that here.

Commits
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d710320 Minor reword
864c4da Add default indication in input arguments/options description

Author: xabbuh

console/input.rst

@@ -91,11 +91,12 @@ There are three argument variants you can use:
     provided;
 
 ``InputArgument::OPTIONAL``
-    The argument is optional and therefore can be omitted;
+    The argument is optional and therefore can be omitted. This is the default
+    behavior of arguments;
 
 ``InputArgument::IS_ARRAY``
     The argument can contain any number of values. For that reason, it must be
-    used at the end of the argument list
+    used at the end of the argument list.
 
 You can combine ``IS_ARRAY`` with ``REQUIRED`` and ``OPTIONAL`` like this::
 
@@ -177,11 +178,15 @@ There are four option variants you can use:
 
 ``InputOption::VALUE_IS_ARRAY``
     This option accepts multiple values (e.g. ``--dir=/foo --dir=/bar``);
+
 ``InputOption::VALUE_NONE``
-    Do not accept input for this option (e.g. ``--yell``);
+    Do not accept input for this option (e.g. ``--yell``). This is the default
+    behavior of options;
+
 ``InputOption::VALUE_REQUIRED``
     This value is required (e.g. ``--iterations=5``), the option itself is
     still optional;
+
 ``InputOption::VALUE_OPTIONAL``
     This option may or may not have a value (e.g. ``--yell`` or
     ``--yell=loud``).