fix #6870 - clairvoyance feedback

Forwarded to the contact form from a github "issue":  in some
circumtances clairvoyance lets you move the cursor around to examine
the revealed map, and when doing so starts with "for instructions
type '?'".  When extended clairvoyance periodically kicks in, as
opposed to explicitly casting the spell, there wasn't sufficient
context to figure out what it was prompting for (unless you actually
answer '?' to get instructions).  Depending upon the most recent
message, it could seem like quite a strange prompt.  Explicitly give
a clairvoyance-specific message prior to that.

Also, the getpos() help was including suggestions for targetting
monsters that aren't appropriate when it's being used for detection.

do_name.c has had quite a bit of formatting rot slip in since 3.6.0.
This fixes up the stuff I spotted by manual inspection.

doc/fixes36.1

@@ -584,6 +584,9 @@ unix: fix for freeing MAIL introduced a one-byte buffer overrun which could
 	interfere with malloc/free operation
 unix: fix for freeing MAIL also introduced a memory leak whenever new mail
 	is detected and MAIL comes from the environment
+when clairvoyance lets you move the cursor to examine the map (if it occurs
+	when engulfed or underwater or when blessed clairvoyance finds a
+	monster), the "for instructions type '?'" prompt could be confusing
 
 
 Platform- and/or Interface-Specific Fixes