indent: README update

Author: pboettch

README.md

@@ -23,10 +23,39 @@ With Vundle
     " inside .vimrc
     Plugin 'pboettch/vim-cmake-syntax'
 
+## Indentation
+
+There is also an indent file which does some intelligent alignment.
+
+For control-keywords (`if`, `while`, `foreach`, `macro`, etc) it automatically adds a
+`shiftwidth()` (and substracts it for a `end`-keyword).
+
+For commands (so everything which has arguments between parenthesis `(...)`) is tries to do the following.
+
+Either it aligns all arguments on a new line in the same column as the opening parenthesis if the first argument is on the
+same line as the command:
+
+```cmake
+add_custom_target(TARGET name
+				  DEPENDS target
+				  WORKING_DIRECTORY ${CMAKE_BINARY_DIR})
+```
+
+or it indents it with one additional `shiftwidth()` if the first argument is on a new line
+
+```cmake
+add_custom_target(
+    TARGET name
+    DEPENDS target
+    WORKING_DIRECTORY ${CMAKE_BINARY_DIR})
+```
+
 ## Test
 
 There is a ever growing test-suite based on ctest located in test/
 
     cd <build-dir-where-ever-located>
     cmake path/to/this/repo/test
     ctest
+
+