Makefile: update static target for Ubuntu 20.04+

Makefile

@@ -58,10 +58,9 @@ $(PROG):
 
 static:
 	$(CC) $(CFLAGS) \
-		-no-pie -fno-PIE \
 		$(XMPPIPE_CFLAGS) \
 		-o xmppipe src/*.c -Wl,--no-as-needed \
-		$(LDFLAGS) -ldl -lz -lresolv \
+		$(LDFLAGS) -ldl -lpthread -lz -lresolv \
 		-l:libstrophe.a \
 		-l:libssl.a -l:libcrypto.a \
 		-l:libexpat.a

README.md

@@ -383,7 +383,7 @@ Format
 Each message is terminated by a new line. Message fields are separated by
 ":" and percent encoded.
 
-Colon separated valued are accepted as input if the input format type
+Colon separated values are accepted as input if the input format type
 is set to csv (`--format=csv`).
 
 ### Presence