Online docs have broken links

[Sam Roberts]

I ran linklint on the output of `make install_html_docs`, and there
are a fair amount of refs to non-existent pages as well. Maybe its
worth adding a `test-docs` target?

Would PRs to fix the below be welcomed?

#------------------------------------------------------------
# ERROR  18 missing html files (cross referenced)
#------------------------------------------------------------
/../man1/version.html
    used in 1 file:
    /man3/CTLOG_STORE_new.html

/../man3/EVP_EncryptInit.html
    used in 1 file:
    /man3/EVP_CIPHER_meth_new.html

/../man3/OSSL_STORE_SEARCH.html
    used in 3 files:
    /man3/OSSL_STORE_expect.html
    /man3/OSSL_STORE_find.html
    /man3/OSSL_STORE_supports_search.html

/../man3/SSL_CTX_set_security_level.html
    used in 2 files:
    /man1/ciphers.html
    /man1/openssl-ciphers.html

/../man7/bio.html
    used in 4 files:
    /man3/BIO_pop.html
    /man3/BIO_push.html
    /man3/BIO_should_retry.html
    /man3/SCT_print.html

/man1/curl.html
    used in 2 files:
    /man1/openssl-tsget.html
    /man1/tsget.html

/man1/perl.html
    used in 2 files:
    /man1/openssl-ts.html
    /man1/ts.html

/man1/procmail.html
    used in 2 files:
    /man1/openssl-ts.html
    /man1/ts.html

/man3/EVP_MD_CTX_set_ctx.html
    used in 2 files:
    /man3/EVP_DigestSignInit.html
    /man3/EVP_DigestVerifyInit.html

/man3/EVP_bf.html
    used in 5 files:
    /man3/EVP_CIPHER_CTX_reset.html
    /man3/EVP_DecryptInit.html
    /man3/EVP_DecryptInit_ex.html
    /man3/EVP_EncryptInit.html
    /man3/EVP_EncryptInit_ex.html

/man3/EVP_cast5.html
    used in 5 files:
    /man3/EVP_CIPHER_CTX_reset.html
    /man3/EVP_DecryptInit.html
    /man3/EVP_DecryptInit_ex.html
    /man3/EVP_EncryptInit.html
    /man3/EVP_EncryptInit_ex.html

/man3/EVP_desx.html
    used in 5 files:
    /man3/EVP_CIPHER_CTX_reset.html
    /man3/EVP_DecryptInit.html
    /man3/EVP_DecryptInit_ex.html
    /man3/EVP_EncryptInit.html
    /man3/EVP_EncryptInit_ex.html

/man3/EVP_idea.html
    used in 5 files:
    /man3/EVP_CIPHER_CTX_reset.html
    /man3/EVP_DecryptInit.html
    /man3/EVP_DecryptInit_ex.html
    /man3/EVP_EncryptInit.html
    /man3/EVP_EncryptInit_ex.html

/man3/EVP_rc2.html
    used in 5 files:
    /man3/EVP_CIPHER_CTX_reset.html
    /man3/EVP_DecryptInit.html
    /man3/EVP_DecryptInit_ex.html
    /man3/EVP_EncryptInit.html
    /man3/EVP_EncryptInit_ex.html

/man3/EVP_rc5.html
    used in 5 files:
    /man3/EVP_CIPHER_CTX_reset.html
    /man3/EVP_DecryptInit.html
    /man3/EVP_DecryptInit_ex.html
    /man3/EVP_EncryptInit.html
    /man3/EVP_EncryptInit_ex.html

/man3/EVP_seed.html
    used in 5 files:
    /man3/EVP_CIPHER_CTX_reset.html
    /man3/EVP_DecryptInit.html
    /man3/EVP_DecryptInit_ex.html
    /man3/EVP_EncryptInit.html
    /man3/EVP_EncryptInit_ex.html

/man3/EVP_sm4.html
    used in 5 files:
    /man3/EVP_CIPHER_CTX_reset.html
    /man3/EVP_DecryptInit.html
    /man3/EVP_DecryptInit_ex.html
    /man3/EVP_EncryptInit.html
    /man3/EVP_EncryptInit_ex.html

/man3/X509_check_purpose.html
    used in 1 file:
    /man3/X509_get_extension_flags.html