* Fix obsolete Microsoft edX courses

Solves part of EbookFoundation/free-programming-books#5112

* Fix with stable alternative for "Hg Init" guide

Solves part of EbookFoundation/free-programming-books#5112

@hginit https://github.com/hginit/hginit.github.ioCo-authored-by: Nhginit <hginit@captnemo.in>
Co-authored-by: Ncaptn3m0 <github.contact@captnemo.in>

* Use wayback machine to recover FindLectures.com

Solves part of EbookFoundation/free-programming-books#5112

Only works first page of mirror
Co-authored-by: Nhginit <hginit@captnemo.in>
Co-authored-by: Ncaptn3m0 <github.contact@captnemo.in>