DOC: fix a few remainig cases of "Haproxy" and "HAproxy" in doc and comments

Some of the Lua doc and a few places still used "Haproxy" or "HAproxy".
There was even one "HA proxy". A few of them were in an example of VTest
output, indicating that VTest ought to be fixed as well. No big deal but
better address all the remaining ones so that these inconsistencies stop
spreading around.
diff --git a/doc/lua-api/index.rst b/doc/lua-api/index.rst
index fb7eb09..e0bda2d 100644
--- a/doc/lua-api/index.rst
+++ b/doc/lua-api/index.rst
@@ -488,7 +488,7 @@
   end)
 ..
 
-  This example code is used in HAproxy configuration like this:
+  This example code is used in HAProxy configuration like this:
 
 ::
 
@@ -511,7 +511,7 @@
   core.register_action("hello-world", { "tcp-req", "http-req" }, hello_world, 2)
 ..
 
-  This example code is used in HAproxy configuration like this:
+  This example code is used in HAProxy configuration like this:
 
 ::
 
@@ -635,7 +635,7 @@
   end)
 ..
 
-  This example code is used in HAproxy configuration like this:
+  This example code is used in HAProxy configuration like this:
 
 ::
 
@@ -2808,7 +2808,7 @@
 
   This attribute is an integer (6). It aborts the current message. The message
   processing is stopped and the transaction is terminated. For HTTP streams,
-  HAproxy assumes a response was already sent to the client. From the Lua
+  HAProxy assumes a response was already sent to the client. From the Lua
   actions point of view, when this code is used, the transaction is terminated
   with no reply.