utils/misc/vim: added Makefile to install vim scripts

- 'make install' copies the files to home .vim folder
- updated README to reflect the new command

Makefile

@@ -0,0 +1,7 @@
+all:
+
+install:
+	mkdir -p ~/.vim/ftdetect
+	mkdir -p ~/.vim/syntax
+	cp ftdetect/ser.vim ~/.vim/ftdetect/
+	cp syntax/ser.vim ~/.vim/syntax/

README

@@ -1,12 +1,18 @@
+Overview
+--------
+
 Vim scripts to auto-detect SER and Kamailio configuration files and
 enable syntax highlighting for them.
 
-Install:
+Install
+-------
 
-- copy ftdetect/ser.vim to ~/.vim/ftdetect/ser.vim
-- copy syntax/ser.vim to ~/.vim/syntax/ser.vim
+Run 'make install' in this folder, or:
+	- copy ftdetect/ser.vim to ~/.vim/ftdetect/ser.vim
+	- copy syntax/ser.vim to ~/.vim/syntax/ser.vim
 
-Usage:
+Usage
+-----
 
 - autodetection is based on .cfg extension and match of #!SER,
 #!KAMAILIO (and other variants), modparam or route keywords in