[Doc] Update PyTorch interface documentation (#4311)
[Doc] Update PyTorch interface documentation (#4311)

* Update interacting with PyTorch

* Update external array indexing

* Update external.md

* Update external.md

* Auto Format

* Update docs/lang/articles/basic/external.md

Co-authored-by: Vissidarte-Herman <bb38b48046b6557306e3b6798e1a0188f4c150c8@users.noreply.github.com>

* Update docs/lang/articles/basic/external.md

Co-authored-by: Vissidarte-Herman <bb38b48046b6557306e3b6798e1a0188f4c150c8@users.noreply.github.com>

* Update docs/lang/articles/basic/external.md

Co-authored-by: Vissidarte-Herman <bb38b48046b6557306e3b6798e1a0188f4c150c8@users.noreply.github.com>

* Update docs/lang/articles/basic/external.md

Co-authored-by: Vissidarte-Herman <bb38b48046b6557306e3b6798e1a0188f4c150c8@users.noreply.github.com>

* Update docs/lang/articles/basic/external.md

Co-authored-by: Vissidarte-Herman <bb38b48046b6557306e3b6798e1a0188f4c150c8@users.noreply.github.com>

* Update docs/lang/articles/basic/external.md

Co-authored-by: Vissidarte-Herman <bb38b48046b6557306e3b6798e1a0188f4c150c8@users.noreply.github.com>

Co-authored-by: Taichi Gardener <52844ac7498fba84f633481a7c3ae54491811c81@gmail.com>
Co-authored-by: Ye Kuang <4b45f682edc0f60a7ee973114ff9390ff2416366@users.noreply.github.com>
Co-authored-by: Vissidarte-Herman <bb38b48046b6557306e3b6798e1a0188f4c150c8@users.noreply.github.com>
yuanming-hu/taichi,yuanming-hu/taichi,yuanming-hu/taichi,yuanming-hu/taichi