Indices are (now) green, bold, right-aligned (#2181)

With https://github.com/nushell/nushell/pull/355 the (numeric) index column of tables was changed to be right-aligned. After the move to `nu-table` the index column is now centered instead of right-aligned. I think this is a copy-paste bug where [this line](71e55541d7/crates/nu-cli/src/commands/table.rs (L190)) has been copied from [this line](71e55541d7/crates/nu-cli/src/commands/table.rs (L207)), since the code is out-of-sync with the comment. This change restores harmony between the description and the function of the code.

crates/nu-cli/src/commands/table.rs

@@ -187,7 +187,7 @@ fn values_to_entries(
                 StyledString::new(
                     (starting_idx + idx).to_string(),
                     TextStyle {
-                        alignment: Alignment::Center,
+                        alignment: Alignment::Right,
                         color: Some(ansi_term::Color::Green),
                         is_bold: true,
                     },