document plots diff/show --open flag (#2293)

Author: skshetry

content/docs/command-reference/plots/diff.md

@@ -11,7 +11,7 @@ usage: dvc plots diff [-h] [-q | -v]
                       [-t <name_or_path>] [-x <field>] [-y <field>]
                       [--no-header] [--title <text>]
                       [--x-label <text>] [--y-label <text>] [-o <path>]
-                      [--show-vega]
+                      [--show-vega] [--open]
                       [revisions [revisions ...]]
 
 positional arguments:
@@ -91,6 +91,8 @@ all the current plots, without comparisons.
   [Vega specification](https://vega.github.io/vega/docs/specification/) file
   instead of HTML. See `dvc plots` for more info.
 
+- `--open` - opens the generated plot directly in the browser.
+
 - `--no-header` - lets DVC know that CSV or TSV `--targets` do not have a
   header. A 0-based numeric index can be used to identify each column instead of
   names.

content/docs/command-reference/plots/show.md

@@ -8,7 +8,7 @@ Generate [plot](/doc/command-reference/plots) from a metrics file.
 usage: dvc plots show [-h] [-q | -v] [-t <name_or_path>] [-x <field>]
                       [-y <field>] [--no-header] [--title <text>]
                       [--x-label <text>] [--y-label <text>] [-o <path>]
-                      [--show-vega]
+                      [--show-vega] [--open]
                       [targets [targets ...]]
 
 positional arguments:
@@ -65,6 +65,8 @@ please see `dvc plots`.
   [Vega specification](https://vega.github.io/vega/docs/specification/) file
   instead of HTML. See `dvc plots` for more info.
 
+- `--open` - opens the generated plot directly in the browser.
+
 - `--no-header` - lets DVC know that CSV or TSV `targets` do not have a header.
   A 0-based numeric index can be used to identify each column instead of names.