Transition handbook links to `https`

This Changes the last few occurences.

Closes #959

README.md

@@ -1,6 +1,6 @@
 [![Build status](https://ci.appveyor.com/api/projects/status/v8o167109n3irf5c/branch/main?svg=true)](https://ci.appveyor.com/project/mih/book/branch/main)
 [![Monthly link check](https://github.com/datalad-handbook/book/actions/workflows/linkcheck.yml/badge.svg)](https://github.com/datalad-handbook/book/actions/workflows/linkcheck.yml)
-[![Documentation Status](https://readthedocs.org/projects/datalad-handbook/badge/?version=latest)](http://handbook.datalad.org/en/latest/?badge=latest)
+[![Documentation Status](https://readthedocs.org/projects/datalad-handbook/badge/?version=latest)](https://handbook.datalad.org/en/latest/?badge=latest)
 [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.3608611.svg)](https://doi.org/10.5281/zenodo.3608611)
 [![made-with-datalad](https://www.datalad.org/badges/made_with.svg)](https://datalad.org)
 <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->

artwork/OHBM_2020.svg

@@ -3356,8 +3356,8 @@
            id="g6756"
            transform="translate(0,-863.42482)">
           <a
-             target="http://handbook.datalad.org/en/latest/basics/intro.html"
-             xlink:href="http://handbook.datalad.org/en/latest/basics/intro.html"
+             target="https://handbook.datalad.org/en/latest/basics/intro.html"
+             xlink:href="https://handbook.datalad.org/en/latest/basics/intro.html"
              id="a3583"
              transform="translate(-1.0583333,8.9958338)">
             <g
@@ -4597,8 +4597,8 @@
             </g>
           </a>
           <a
-             target="http://handbook.datalad.org/en/latest/intro/philosophy.html"
-             xlink:href="http://handbook.datalad.org/en/latest/intro/philosophy.html"
+             target="https://handbook.datalad.org/en/latest/intro/philosophy.html"
+             xlink:href="https://handbook.datalad.org/en/latest/intro/philosophy.html"
              id="a3552"
              transform="translate(0,17.991672)">
             <g
@@ -4758,8 +4758,8 @@
             </g>
           </a>
           <a
-             target="http://handbook.datalad.org/en/latest/usecases/intro.html"
-             xlink:href="http://handbook.datalad.org/en/latest/usecases/intro.html"
+             target="https://handbook.datalad.org/en/latest/usecases/intro.html"
+             xlink:href="https://handbook.datalad.org/en/latest/usecases/intro.html"
              id="a3888"
              transform="translate(0,13.229169)">
             <g