[v16.x] doc: include git add -f to include folder

[RafaelGSS]

Ref:

$ git add deps/openssl/openssl/include/openssl/opensslconf.h
The following paths are ignored by one of your .gitignore files:
deps/openssl/openssl/include/openssl/opensslconf.h
hint: Use -f if you really want to add them.
hint: Turn this message off by running
hint: "git config advice.addIgnoredFile false"

The .gitignore from quictls/openssl is read by git so we need to force include it

[nodejs-github-bot]

Review requested:

• @nodejs/tsc

[richardlau]

The .gitignore from quictls/openssl is read by git so we need to force include it

I don't object to the change being proposed by this PR, but it should be unnecessary -- the .gitignore file being referenced should have been removed by

node/doc/contributing/maintaining-openssl.md

Line 70 in 76f9a7d

% rm -rf openssl/.git* openssl/.travis*