Update ACL plugin's README to capture the edge case (#5311)
Update ACL plugin's README to capture the edge case (#5311)

* Update ACL plugin's README to capture the edge case

This PR adds a note in ACL plugin's README to capture the edge case
where source ip of the client may be different from the source ip
observed by coredns server (in situations such as Source NAT).

Signed-off-by: Yong Tang <765086fe2e0c1f980161f127fec596800f327f62@outlook.com>

* Update plugin/acl/README.md

Co-authored-by: Chris O'Haver <c8d69f6e0f4a592980d82af78b0efddff3dcc387@infoblox.com>
Signed-off-by: Yong Tang <765086fe2e0c1f980161f127fec596800f327f62@outlook.com>

* Update plugin/acl/README.md

Co-authored-by: Chris O'Haver <c8d69f6e0f4a592980d82af78b0efddff3dcc387@infoblox.com>
Signed-off-by: Yong Tang <765086fe2e0c1f980161f127fec596800f327f62@outlook.com>

Co-authored-by: Chris O'Haver <c8d69f6e0f4a592980d82af78b0efddff3dcc387@infoblox.com>
coredns/coredns,yongtang/coredns,chrisohaver/coredns