cmd-ref: plots: flexible plots docs

Related: treeverse/dvc#7477
Related: treeverse#2956

Author: pared

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

@@ -1,7 +1,7 @@
 # plots diff
 
-Show multiple versions of [plot metrics](/doc/command-reference/plots) by
-overlaying them in a single image. This allows to compare them easily.
+Show multiple versions of [plots](/doc/command-reference/plots) by overlaying
+them in a single image. This allows to compare them easily.
 
 ## Synopsis
 
@@ -122,11 +122,11 @@ file:///Users/usr/src/dvc_plots/index.html
 Compare two specific versions (commit hashes, tags, or branches):
 
 ```cli
-$ dvc plots diff HEAD 0135527 --targets logs.csv
+$ dvc plots diff HEAD^ 0135527 --targets logs.csv
 file:///Users/usr/src/dvc_plots/index.html
 ```
 
-![](/img/plots_diff.svg)
+![](/img/plots_diff_two_revs.svg)
 
 ## Example: Confusion matrix