Update directive map for max_headers

[dekobon]

Add the max_headers directive entry to match the upstream NGINX change. The directive limits the number of request headers and is valid in the http and server contexts with a single argument.

Proposed changes

Updates the nginx-go-crossplane directive map to include the new max_headers directive, which was backported from freenginx into mainline NGINX. The directive is valid in the http and server contexts and takes a single argument. This is a companion change for the NGINX backport of the max_headers directive.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• I have updated any relevant documentation (README.md)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.20%. Comparing base (eaaaa89) to head (2a430e7).
⚠️ Report is 34 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #174      +/-   ##
==========================================
+ Coverage   76.63%   78.20%   +1.56%     
==========================================
  Files          27       31       +4     
  Lines        1164     1179      +15     
==========================================
+ Hits          892      922      +30     
+ Misses        216      202      -14     
+ Partials       56       55       -1     

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[ornj]

Looks right to me.

    { ngx_string("max_headers"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_core_srv_conf_t, max_headers),
      NULL },