maint: Add postinstall script to upgrade dev.

Note: the "make upgrade" target is run in the directory where npm
install is invoked. If you install "@patternslib/dev" as a dependency in
"@pattersnlib/patternslib", the Patternslib project is upgraded.

Author: thet

Makefile

@@ -171,4 +171,5 @@ serve: install
 	$(YARN) run start
 
 
-#
+upgrade:
+	@# Upgrade target, depends on other upgrades

README.md

@@ -1,7 +1,17 @@
 # Development helpers and config for Patternslib and add-ons.
 
+This repository includes base files which are extended in Patternslib, Mockup or other projects.
+
+It includes a Makefile which helps in installing and releasing packages.
+
+## Upgrading
+
+Run `make upgrade` in your project.
+
+Alternatively, if there is a new `@patternslib/dev` version installed, the `postinstall` package.json script will automatically run `make upgrade` in the directory where package installer was invoked, that is your project directory which depends on `@patternslib/dev`.
+
+
 ## Code style
 
-The release process based on release-it includes automatic changelog generation via conventional-commit, commitlint and a pre-commit hook by husky.
+The release process based on release-it includes automatic changelog generation via conventional-commit, commitlint and a git pre-commit hook.
 Please check the [code style guide](https://github.com/Patternslib/Patterns/blob/master/docs/developer/styleguide.md#commits-messages) for the commit specification!
-

package.json

@@ -37,6 +37,7 @@
         "node": ">=18.18"
     },
     "scripts": {
+        "postinstall": "cd $INIT_CWD && make upgrade",
         "test": "jest"
     },
     "author": {