Added INSTALL file with fresh instructions.

Borrowed from Codeine and changed to suit KlamAV.

Signed-off-by: Mavridis Philippe <mavridisf@gmail.com>

INSTALL

@@ -0,0 +1,22 @@
+Basic Installation
+==================
+
+KlamAV relies on CMake to build.
+
+Here are suggested default options:
+
+ -DCMAKE_INSTALL_PREFIX="/opt/trinity" \
+ -DCONFIG_INSTALL_DIR="/etc/trinity" \
+ -DSYSCONF_INSTALL_DIR="/etc/trinity" \
+ -DXDG_MENU_INSTALL_DIR="/etc/xdg/menus" \
+ -DCMAKE_BUILD_TYPE=RelWithDebInfo \
+ -DCMAKE_VERBOSE_MAKEFILE="ON" \
+ -DCMAKE_SKIP_RPATH="OFF" \
+ -DBUILD_ALL="ON" \
+ -DWITH_ALL_OPTIONS="ON"
+
+
+Requirements:
+=============
+
+- ClamAV ≥ 0.102