Need to reword post installation instruction in post-install script

Build tested: 1.4.0-1

engine commit:
1f47534

Distributed installation is no longer supported. Installation is always non-distributed.

Currently, post-install script outputs the following instruction:

The next step is:

If installing on a pm1 node using non-distributed install

/usr/local/mariadb/columnstore/bin/postConfigure

If installing on a pm1 node using distributed install

/usr/local/mariadb/columnstore/bin/postConfigure -d

If installing on a non-pm1 using the non-distributed option:

/usr/local/mariadb/columnstore/bin/columnstore start

We should make as the following:

The next step is:

If installation on pm1:

/usr/local/mariadb/columnstore/bin/postConfigure

If installing on a node other than pm1:

/usr/local/mariadb/columnstore/bin/columnstore start