Typos in quick trial description for "HelloThemisto"

[zrlhle]

1. two "-" needed in front of "recursive" option
   git clone -recursive git@github.com:cloudFPGA/cFp_HelloThemisto.git --> git clone --recursive git@github.com:cloudFPGA/cFp_HelloThemisto.git
2. ./sra/build pr --> ./sra build pr

[fab7]

The PR flow of the file
Doc/docsrc/pages/GETTING_STARTED/getting_started.md
was updated as well as the related cFp_HelloThemisto project.

[zrlhle]

Thank you