fix development script and instructions

[dalehenrich]

Prerequisite to Issue #263 and follow-on to Issue #261:

• update readme to mention that updateGsDevKit -gdtcs is only needed if updating an existing GsDevKit_home clone where at least one stone has been created ..
• insert call to $GS_HOME/bin/private/shFunctions in alt_bin/bootstrap_launcher -- not working as expected (see realpath in ${GS_HOME}/bin/private/shFunctions not adequate replacement for bash realpath #268) ... https://github.com/mkropat/sh-realpath appears to work (on linux)
• newBuild_SystemUser_gsdevkit_launcher_tode (and probably the other dev scripts) are dependent upon st_launcher ... need to rewrite the script to use here docs with topaz ...
• add additional examples that include using the --help option (to explain what the -D option does
• need confirmation from @brunobuzzi and @JupiterJones that https://github.com/mkropat/sh-realpath works in their environment
  • confirmed on mac
  • confirmed on linux without realpath installed