Description of problem: Update man page for ipa-adtrust-install by removing --no-msdcs option

Version-Release number of selected component (if applicable):
ipa-server-trust-ad-4.4.0-14.el7_3.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Run ipa-adtrust-install --help
2. Check the output.

Actual results:
Options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit
  -d, --debug           print debugging information
  --netbios-name=NETBIOS_NAME
                        NetBIOS name of the IPA domain
  --rid-base=RID_BASE   Start value for mapping UIDs and GIDs to RIDs
  --secondary-rid-base=SECONDARY_RID_BASE
                        Start value of the secondary range for mapping UIDs
                        and GIDs to RIDs
  -U, --unattended      unattended installation never prompts the user
  -a ADMIN_PASSWORD, --admin-password=ADMIN_PASSWORD
                        admin user kerberos password
  -A ADMIN_NAME, --admin-name=ADMIN_NAME
                        admin user principal
  --add-sids            Add SIDs for existing users and groups as the final
                        step
  --add-agents          Add IPA masters to a list of hosts allowed to
                        serveinformation about users from trusted forests
  --enable-compat       Enable support for trusted domains for old clients

Expected results:
It doesn't list any option for '--no-msdcs' which is deprecated.
So we should be removing it from man page.

Additional info:
--no-msdcs
Do not create DNS service records for Windows in managed DNS server. Since those DNS service records are the only way to discover domain controllers of other domains they must be added manually to a different DNS server to allow trust reala‐tionships  work  properly. All needed service records are listed when ipa-adtrust-install finishes and either --no-msdcs was given or no IPA DNS service is configured. Typically service records for the following service names are needed  for the IPA domain which should point to all IPA servers:

· _ldap._tcp
· _kerberos._tcp
· _kerberos._udp
· _ldap._tcp.dc._msdcs
· _kerberos._tcp.dc._msdcs
· _kerberos._udp.dc._msdcs
· _ldap._tcp.Default-First-Site-Name._sites.dc._msdcs
· _kerberos._tcp.Default-First-Site-Name._sites.dc._msdcs
· _kerberos._udp.Default-First-Site-Name._sites.dc._msdcs