docs: add cainfo cli reference imported from CAref.html

modules/ca/src/tools/Makefile

@@ -25,5 +25,6 @@ cainfo_SRCS = cainfo.c
 PROD_LIBS = ca Com
 
 DOCS += caget.md
+DOCS += cainfo.md
 
 include $(TOP)/configure/RULES

modules/ca/src/tools/cainfo.md

@@ -0,0 +1,40 @@
+# cainfo
+
+``` {program} cainfo
+```
+
+    cainfo [options] <PV name> ...
+
+## Description
+
+Get and print channel and connection information for PV(s).
+
+All available Channel Access related information about PV(s) is printed
+to stdout.
+
+The {option}`-s` option allows to specify an interest level for calling Channel
+Access' internal report function `ca_client_status()`, that prints lots
+of internal informations on stdout, including environment settings, used
+CA ports etc.
+
+## Options
+
+::: {option} -h
+Print usage information
+:::
+
+### CA options
+
+::: {option} -w <sec>
+Wait time, specifies longer CA timeout, default is 1.0 second.
+:::
+
+::: {option} -s <level>
+Call ca_client_status with the specified interest level
+:::
+
+::: {option} -p <prio>
+CA priority (0--99, default 0=lowest)
+:::
+
+