11628 typos detected by mandoc style

@@ -9,11 +9,11 @@
 .\" http://www.illumos.org/license/CDDL.
 .\"
 .\"
 .\" Copyright 2016 Joyent, Inc.
 .\"
-.Dd "Jan 13, 2015"
+.Dd "Aug 27, 2019"
 .Dt THRD_JOIN 3C
 .Os
 .Sh NAME
 .Nm thrd_join
 .Nd wait for thread termination

@@ -25,11 +25,11 @@
 .Fa "int *res"
 .Fc
 .Sh DESCRIPTION
 The
 .Fn thrd_join
-function suspends the exection of the current thread and waits for the
+function suspends the execution of the current thread and waits for the
 thread indicated by
 .Fa thrd
 to terminate and stores the exit status, as set by a call to
 .Xr thrd_exit 3C ,
 for that thread in

@@ -57,11 +57,11 @@
 For additional information on the thread joining interfaces supported by
 the system, see
 .Xr pthread_join 3C
 and
 .Xr thr_join 3C .
-.Sh RETURN_VALUES
+.Sh RETURN VALUES
 Upon successful completion, the
 .Fn thrd_join
 function returns
 .Sy thrd_success
 and if