merge SC3046 SC3051 ("In POSIX sh, source in place of . is undefined")

[jmuf]

Both SC3046 and SC3051 give the same warning:

In code/files/collect_data.sh line 7:
    source /etc/sysconfig/someenv
    ^---------------------------^ SC3046 (warning): In POSIX sh, 'source' in place of '.' is undefined.
    ^---------------------------^ SC3051 (warning): In POSIX sh, 'source' in place of '.' is undefined.

The help texts in the Wiki differ slightly (absolute path sourced in example for SC3051 and hint on $PATH, no path in SC3046) - suggest to drop SC3046.