Restructure docker-compose

* Use alpine images
* Remove separate directory
* Give more hints in docker-compose file

.editorconfig

@@ -0,0 +1,24 @@
+# EditorConfig is awesome: https://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+# Matches multiple files with brace expansion notation
+# Set default charset
+[*.*]
+charset = utf-8
+
+# Tab indentation (no size specified)
+[Makefile]
+indent_style = tab
+
+# Matches the files *.yml
+[*.yml]
+indent_style = space
+indent_size = 2
+