Fix typos (spelling errors) in install files.

# New Ticket Created by  (Peter J. Acklam)
# Please include the string:  [perl #81886]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=81886 >

Signed-off-by: Abigail <abigail@abigail.be>

INSTALL

@@ -984,7 +984,7 @@ Perl comes with interfaces to number of libraries, including threads,
 dbm, ndbm, gdbm, and Berkeley db.  For the *db* extension, if
 Configure can find the appropriate header files and libraries, it will
 automatically include that extension.  The threading extension needs
-to be specified explicitely (see L<Threads>).
+to be specified explicitly (see L<Threads>).
 
 Those libraries are not distributed with perl. If your header (.h) files
 for those libraries are not in a directory normally searched by your C

installhtml

@@ -170,7 +170,7 @@ $pod2html = "pod/pod2html";
 usage("") unless @ARGV;
 
 # Overcome shell's p1,..,p8 limitation.  
-# See vms/descrip_mms.template -> descrip.mms for invokation.
+# See vms/descrip_mms.template -> descrip.mms for invocation.
 if ( $^O eq 'VMS' ) { @ARGV = split(/\s+/,$ARGV[0]); }
 
 use vars qw( %Options );

installperl

@@ -165,7 +165,7 @@ foreach my $ext_dir (@ext_dirs) {
 	{
 	    my($path, $modname) = ($1,$2);
 
-	    # Change hypenated name like Filter-Util-Call to nested
+	    # Change hyphenated name like Filter-Util-Call to nested
 	    # directory name Filter/Util/Call
 	    $path =~ s{-}{/}g;