Document the OpenOCD installation with specific examples for package
managers and move the installation section to the beginning of the
document to make it more prominent.
Change-Id: I86e175fdd4060b49070a5c8d2b92ec1c6cfe6acf
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: https://review.openocd.org/c/openocd/+/9395
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>