Changelog entry and docs update for #7402

Author: ptkato

changelog.d/pr-7402

@@ -0,0 +1,13 @@
+synopsis: changes to cabal v2-configure
+packages: cabal-install
+prs: #7402
+issues: #5591 #7180 #7405
+
+description: {
+
+- Removes the --dry-run part of the v2-configure command
+- Adds an --append flag to v2-configure, which allows new configuration to be appended to the old config file
+- Adds an --overwrite flag to v2-configure, which disables the backup feature for the config file
+- Includes unit tests for everything
+
+}

doc/cabal-commands.rst

@@ -42,6 +42,15 @@ to happen if a flag actually applied to every transitive dependency). To
 apply options to an external package, use a ``package`` stanza in a
 ``cabal.project`` file.
 
+There are two ways of modifying the ``cabal.project.local`` file through
+``cabal v2-configure``, either by appending new configurations to it, or 
+by simply overwriting it all. Overwriting is the default behaviour, as
+such, there's a flag ``--enable-append`` to append the new configurations
+instead. Since overwriting is rather destructive in nature, a backup system
+is in place, which moves the old configuration to a ``cabal.project.local~``
+file, this feature can also be disabled by using the ``--enable-overwrite``
+flag.
+
 cabal v2-update
 ----------------