Refine application_pre_install_role variable usage

As 'application_pre_install_role' variable set in
config/application_configuration.yml must stay in
sync with patch role directory name defined in
package.conf under APP_CONFIGURATION variable, it's
name shall stay under complete user control without
any variable as part of it's name.

App_helm_build_targets list and app_helm_chart_name
should default to 'onap' in application_configuration.yml
as customizing them isn't supported at the moment.

Also fixed some wording in comments/docs in relevant
files.

Change-Id: I82b6dd519fbc3426739a11fac1e02eb495a668c0
Issue-ID: OOM-1697
Signed-off-by:  Bartek Grzybowski <b.grzybowski@partner.samsung.com>
diff --git a/build/package.conf b/build/package.conf
index 29ca3cb..7d6a1b8 100644
--- a/build/package.conf
+++ b/build/package.conf
@@ -30,12 +30,12 @@
 
 # APP_CONFIGURATION array variable can be used to provide files/directories
 # into sw package available for the Ansible process to consume.
-# The main configuration for you application is a yml file
+# The main configuration file for your application is
 # "application_configuration.yml" (name of file can be anything) where user
-# need to provide values to control ansible installer process. Yml file is given
+# shall provide values to control ansible installer process. Yml file is given
 # as command line parameter to ansible run.
 # See more from UserGuide documentation (LINK HERE) how to use installer.
-# Available configuration parameters user can configure is seen from group_vars files:
+# Available configuration parameters user can configure are seen from group_vars files:
 #   ansible/group_vars/all.yml
 #   ansible/group_vars/infrastucture.yml
 #   ansible/group_vars/kubernetes.yml
@@ -46,10 +46,10 @@
 #   application_pre_install_role: my-pre-install-role
 #   application_post_install_role: my-post-install-role
 # And according to Ansible functionality, roles' code must be placed to directories
-# with the same name.
+# with the same name:
 #APP_CONFIGURATION=(
 #    <offline-installer-clone>/config/application_configuration.yml
-#    <offline-installer-clone>/patches/onap-casablanca-patch-role
+#    <offline-installer-clone>/patches/my-pre-install-role
 #    ~/myappfiles/my-post-install-role
 #)
 APP_CONFIGURATION=(