Documentation updated.

scrbl/keystore.scrbl

@@ -24,9 +24,12 @@ stringified lowercase form, which allows glob-style queries.
 Represents an open keystore. The @racket[file] field contains the
 original argument, @racket[path] is the resolved database path, and
 @racket[dbh] is the SQLite connection.
+
+The @tt{keystore?} predicate is altered to also check if the
+database connection is (still) valid.
 }
 
-@section{Opening}
+@section{Opening & Closing}
 
 @defproc[(ks-open [file (or/c path? string? symbol?)]) keystore?]{
 
@@ -35,6 +38,12 @@ location is used; otherwise it is interpreted as a filesystem path.
 The database schema is created automatically if it does not yet exist.
 }
 
+@defproc[(ks-close [ks keystore?]) boolean?]{
+
+Closes the keystore. The keystore handle is invalidated after closing
+the underlying storage (database). 
+}
+
 @section{Basic Operations}
 
 @defproc[(ks-set! [ks keystore?] [key any/c] [value any/c]) boolean?]{