src: Fix typo

Apply typo fixes to the original source files in the previous commit
which were done in generated text.

src/nghttp.cc

@@ -2398,7 +2398,7 @@ Options:
               Discard downloaded data.
   -O, --remote-name
               Save  download  data  in  the  current  directory.   The
-              filename is  dereived from URI.   If URI ends  with '/',
+              filename is  derived from  URI.  If  URI ends  with '/',
               'index.html'  is used  as a  filename.  Not  implemented
               yet.
   -t, --timeout=<DURATION>

src/shrpx.cc

@@ -1213,7 +1213,7 @@ Performance:
               Set   maximum  number   of  backend   concurrent  HTTP/1
               connections per origin host.   This option is meaningful
               when -s option  is used.  The origin  host is determined
-              by  authority  portion  of requset  URI  (or  :authority
+              by  authority  portion  of request  URI  (or  :authority
               header  field  for  HTTP/2).   To limit  the  number  of
               connections   per  frontend   for   default  mode,   use
               --backend-http1-connections-per-frontend.