Several doc fixes for events

pkgs/racket-pkgs/racket-doc/scribblings/reference/evts.scrbl

@@ -32,7 +32,7 @@ event's state.
 
 Racket values that act as @tech{synchronizable events} include
 @tech{semaphores}, @tech{channels}, @tech{asynchronous channels},
-@tech{ports}, @tech{TCP listeners}, @tech{threads},
+@tech{ports}, @tech{TCP listeners}, @tech{log receiver}s, @tech{threads},
 @tech{subprocess}es, @tech{will executors}, and @tech{custodian
 box}es. Libraries can define new synchronizable events, especially
 though @racket[prop:evt].

pkgs/racket-pkgs/racket-doc/scribblings/reference/filesystem.scrbl

@@ -492,7 +492,7 @@ event}, @racket[#f] otherwise.}
                                    [failure-thunk (-> any)])
             any])]{
 
-Creates a @deftech{filesystem change event}, which is
+Creates a @deftech{filesystem change event}, which is a
 @tech{synchronizable event} that becomes @tech{ready for
 synchronization} after a change to @racket[path]:
 

pkgs/racket-pkgs/racket-doc/scribblings/reference/networking.scrbl

@@ -510,14 +510,16 @@ address and port, @racket[#f] otherwise.}
 
 Returns a @tech{synchronizable event} (see @secref["sync"]) that is
 in a blocking state when @racket[udp-send-to] on @racket[udp-socket]
-would block.}
+would block. The @tech{synchronization result} is the event itself.
+}
 
 
 @defproc[(udp-receive-ready-evt [udp-socket udp?]) evt?]{
 
 Returns a @tech{synchronizable event} (see @secref["sync"]) that is
 in a blocking state when @racket[udp-receive!] on @racket[udp-socket]
-would block.}
+would block. The @tech{synchronization result} is the event itself.
+}
 
 @defproc[(udp-send-to-evt [udp-socket udp?]
                       [hostname string?]
@@ -542,7 +544,7 @@ bstr start-pos end-pos)], and the synchronization result is
          evt?]{
 
 Returns a @tech{synchronizable event}. The event is @tech{ready for synchronization}
-state when @racket[udp-send] on @racket[udp-socket] would
+when @racket[udp-send] on @racket[udp-socket] would
 not block. Otherwise, if the event is chosen in a synchronization, data is
 sent as for @racket[(udp-send-to udp-socket bstr start-pos end-pos)],
 and the @tech{synchronization result} is @|void-const|. (No bytes are sent if

pkgs/racket-pkgs/racket-doc/scribblings/reference/threads.scrbl

@@ -210,7 +210,7 @@ Returns a @tech{synchronizable event} (see @secref["sync"]) that is
 prevent @racket[thd] from being garbage collected (see
 @secref["gc-model"]). For a given @racket[thd],
 @racket[thread-dead-evt] always returns the same (i.e., @racket[eq?])
-result .@ResultItself{thread-dead event}.}
+result. @ResultItself{thread-dead event}.}
 
 @defproc[(thread-resume-evt [thd thread?]) evt?]{