Fix typo that cause find-doc-nits failure

Reviewed-by: NBen Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/4727)

doc/man3/OCSP_resp_find_status.pod

@@ -34,7 +34,7 @@ OCSP_single_get0_status, OCSP_check_validity
 
  const STACK_OF(X509) *OCSP_resp_get0_certs(const OCSP_BASICRESP *bs);
 
- int OCSP_resp get0_signer(OCSP_BASICRESP *bs, X509 **signer,
+ int OCSP_resp_get0_signer(OCSP_BASICRESP *bs, X509 **signer,
                            STACK_OF(X509) *extra_certs);
 
  int OCSP_resp_get0_id(const OCSP_BASICRESP *bs,