Add cabal target docs

doc/cabal-commands.rst

@@ -213,6 +213,8 @@ Arguments and flags common to some or all commands are:
 
     Already generated `build-info.json` files will be removed since they would be stale otherwise.
 
+.. _target-forms:
+
 Target Forms
 ------------
 
@@ -735,6 +737,20 @@ Examples:
     be used without arguments, in that case major version bumps are ignored for
     all packages.
 
+cabal target
+^^^^^^^^^^^^
+
+``cabal target [TARGETS]`` discloses fully-qualified targets from a selection of
+targets and is useful for discovering targets in a project for use with other
+commands taking [TARGETS]. This command can also check if a :ref:`target
+form<target-forms>` is unique as some commands require a unique TARGET.
+
+Any target forms except for a script target can be used with ``cabal target``.
+
+For a package, all, module or filepath target, cabal target [TARGETS] will
+**only** show ``libs`` and 'exes' of the [TARGETS]. To also show tests and
+benchmarks, enable them with ``--enable-tests`` and ``--enable-benchmarks``.
+
 .. _command-group-build:
 
 Project building and installing