Update README.md

add Windows installation

backend/README.md

@@ -54,3 +54,45 @@ To set config options at runtime, use `environment variables`, `java system prop
 ### State management
 
 Global state (e.g. instances of database and webserver) are managed by [mount](https://github.com/tolitius/mount).
+
+# Installation
+
+## Windows
+
+The backend runs clojure. To install clojure you might use [leiningen](https://leiningen.org/).
+
+### java install
+But first check to have a java installtion ready to run. 
+
+```bash
+java -version
+```
+
+If not - you can download it e.g. from [Adopt](https://adoptopenjdk.net/installation.html#x64_win-jdk). Dowload a LTS and HotSpot Version using the links and commands below "Windows x64 jdk installation". Basically it is just a Unziping and adding PATH to Environment. 
+
+### lein install
+
+consider download, self-install and run via lein.bat 
+ * locally 
+ * or in a folder from your PATH-Variable (call SET in commandline to check)
+
+```bash
+curl https://raw.githubusercontent.com/technomancy/leiningen/stable/bin/lein.bat >lein.bat
+lein run
+```
+
+### debug 
+
+in case of failure you can add detail information by activating verbose-mode
+
+```bash
+SET VERBOSE=true
+lein run
+```
+
+to check using test-data use
+
+```bash
+set DB_SEED="src/beherbergung/db/seed/test.edn"
+lein run
+```