diffpkg: allow to set column width for side-by-side view

The magic values `columns` and `auto` allow to set specific aspects,
with 'auto' as the default value:

- auto: Set width to the maximum line length of all input files
- columns: Set width to the shell defined $COLUMNS env var

Furthermore any number can be passed to set a static width.

1 files changed, 4 insertions, 0 deletions

diff --git a/doc/man/diffpkg.1.asciidoc b/doc/man/diffpkg.1.asciidoc
index ec89f89..69e0c27 100644
--- a/doc/man/diffpkg.1.asciidoc
+++ b/doc/man/diffpkg.1.asciidoc
@@ -48,6 +48,10 @@ Output Options
 *-y, --side-by-side*::
 	Output in two columns
 
+*-W, --width*[='NUM']::
+	Output at most 'NUM' (default `'auto'`) print columns; 'NUM' can be `'auto'`, `'columns'` or a number.
+	`'auto'` will be resolved to the maximum line length of both files, guaranteeing the diff to be uncut.
+
 Modes
 -----