document how to install all pinned requirements
document how to install all pinned requirements

as they are found in two files since 13af4df6bef301b797e165755315e3c276c894e0 (PR #599)

(part of #600)
geometalab/drf-utm-zone-info,geometalab/osmaxx-frontend,geometalab/osmaxx,geometalab/drf-utm-zone-info,geometalab/osmaxx-frontend,geometalab/osmaxx,geometalab/osmaxx-frontend,geometalab/osmaxx,geometalab/osmaxx,geometalab/osmaxx-frontend