[manpages] describe selector and multiselector

doc/man/man3/notcurses_multiselector.3.md

@@ -51,6 +51,11 @@ typedef struct ncmultiselector_options {
 
 # DESCRIPTION
 
+A multiselector widget presents a list of items (possibly more than can be
+displayed at once). It facilitates a choice of zero, one, or multiple items
+from the list. Items can be selected and deselected before a final choice
+is made.
+
 # NOTES
 
 The **ncplane** **n** provided to **ncmultiselector_create** must not be

doc/man/man3/notcurses_selector.3.md

@@ -59,6 +59,10 @@ typedef struct ncselector_options {
 
 # DESCRIPTION
 
+A selector widget presents a list of items (possibly more than can be
+displayed at once). It facilitates a choice of zero or one item from the
+list.
+
 # NOTES
 
 The **ncplane** **n** provided to **ncselector_create** must not be **NULL**.