Update intro_installation.rst

Change 'SSH' to upper case.

Improve documentation.

 * now it uses -n to get immediate error if no password is supplied and one is needed,
   this should fix the issue with sudo hanging waiting for input.
 * made -k configurable, this can break changing become_users in play if left out,
   but opens up the possiblity of OTP support.

Fixes #11968
Fixes #11969

falls back to current service module and requries service mgr facts and new service modules

Fix rm call in hacking/env-setup. Since it is sourced from a user shell,

rm can have an alias to 'rm -i', which will make sourcing hang when '-q'
is enabled.

fixes #11965

Tweak deprecation warning, and apply it to --limit also

Also prints a deprecated warning if a bare variable is detected, so
that we can remove this in a future version.

Fixes #11912

The correct (and now only) way to say p1 OR p2 is "p1:p2".

This function takes a string like 'foo:bar[1:2]:baz[x:y]-quux' and
returns a list of patterns ['foo', 'bar[1:2]', 'baz[x:y]-quux'], i.e.
splits the string on colons that are not part of a range specification.

get_hosts → used externally, not changed
_get_hosts → _evaluate_patterns (takes a list, evaluates ! and &)
__get_hosts → _match_one_pattern (takes one pattern only, ignores !&)

The correct (and now only) way to say p1 OR p2 is "p1:p2".

This function takes a string like 'foo:bar[1:2]:baz[x:y]-quux' and
returns a list of patterns ['foo', 'bar[1:2]', 'baz[x:y]-quux'], i.e.
splits the string on colons that are not part of a range specification.

This was used earlier to implement serial, but that's now done using
restrict_to_hosts() (whose docstring is also suitably adjusted here)
and there are no more callers.

Fix typo on AWS guide page

Fixes #11955

I assume this should read “Ansible modules” rather than “Ansible
ensiles”

Update README.md for legacy v1

Correct formatting of bullet points