Update quickstart.md

kelvinlee@Kelvins-MacBook-Pro Project-Euler-Solutions % echo hello | tee -a $(find -name ./README.txt)
find: illegal option -- n
usage: find [-H | -L | -P] [-EXdsx] [-f path] path ... [expression]
       find [-H | -L | -P] [-EXdsx] -f path [path ...] [expression]
hello

(END)
TEE(1)                    BSD General Commands Manual                   TEE(1)

NAME
     tee -- pipe fitting

SYNOPSIS
     tee [-ai] [file ...]

DESCRIPTION
     The tee utility copies standard input to standard output, making a copy
     in zero or more files.  The output is unbuffered.

     The following options are available:

     -a      Append the output to the files rather than overwriting them.

     -i      Ignore the SIGINT signal.

     The following operands are available:

     file  A pathname of an output file.

     The tee utility takes the default action for all signals, except in the
     event of the -i option.

     The tee utility exits 0 on success, and >0 if an error occurs.

STANDARDS
     The tee function is expected to be POSIX IEEE Std 1003.2 (``POSIX.2'')
     compatible.

BSD                              June 6, 1993                              BSD