minor #7751 Fixed indentation in security.rst (KoenraadM, javiereguiluz)

This PR was submitted for the 3.2 branch but it was merged into the 2.7 branch instead (closes #7751).

Discussion
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Fixed indentation in security.rst

Commits
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1f36811 Use HTTP instead of http
e8c2539 Fixed indentation in security.rst

Author: xabbuh

reference/configuration/security.rst

@@ -114,7 +114,7 @@ Each part will be explained in the next section.
                     pattern: .*
                     # restrict the firewall to a specific host
                     host: admin\.example\.com
-                     # restrict the firewall to specific http methods
+                    # restrict the firewall to specific HTTP methods
                     methods: [GET, POST]
                     request_matcher: some.service.id
                     access_denied_url: /foo/error403