docs: the FAQ document adds the issue of failure to execute the make deps command

[Firstsawyou]

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When deploying APISIX in source code mode, if the openresty-openssl111-devel dependency is missing, the following error message will occur when executing make deps:

$ make deps
......
luasocket 3.0rc1-2 is now installed in /home/apisix/deps (license: MIT)

apisix master-0 depends on luasec 0.9-1 (not installed)
Installing https://luarocks.org/luasec-0.9-1.src.rock

Error: Failed installing dependency: https://luarocks.org/luasec-0.9-1.src.rock - Could not find header file for OPENSSL
  No file openssl/ssl.h in /usr/local/openresty/openssl111/include
You may have to install OPENSSL in your system and/or pass OPENSSL_DIR or OPENSSL_INCDIR to the luarocks command.
Example: luarocks install luasec OPENSSL_DIR=/usr/local
make: *** [deps] error 1

For such common problems, we should record such problems in the FAQ.