As per the feedback at https://github.com/google/fscrypt/issues/115
where users didn't understand that the recovery passphrase is important,
restore the original behavior where recovery passphrase generation
happens automatically without a prompt.  This applies to the case where
'fscrypt encrypt' is using a login protector on a non-root filesystem.

However, leave the --no-recovery option so that the recovery passphrase
can still be disabled if the user really wants to.  Also, clarify the
information provided about the recovery passphrase.

Update https://github.com/google/fscrypt/issues/115

README: mention LTS kernel versions with symlink bug fix

Resolves https://github.com/google/fscrypt/issues/305

In Linux 5.15, the no-key name format is changing again; see
https://git.kernel.org/linus/ba47b515f5940603.  isPossibleNoKeyName()
sometimes doesn't recognize the new no-key names.  Update it accordingly
to recognize all possible no-key names.

Note: isPossibleNoKeyName() is only used as a heuristic to check whether
a v1-encrypted directory is incompletely locked or not.  Therefore, it's
not too important whether it works.  However, this change is needed for
cli-tests/t_v1_policy to pass.

These confuse the latest version of shellcheck into thinking that
functions which take no arguments actually take arguments, which
triggers a bunch of warnings like "Use func "$@" if function's $1 should
mean script's $1", which causes 'make lint' to fail.  These checks
aren't too useful, so just remove them.

Update https://github.com/google/fscrypt/issues/115

Readme updates

Capitalize the first word only, and don't use periods.