doc/tutorian/basics: fix typo

Fixes cuelang/cue#22.

Change-Id: I5c2129a16153dae74fd8262e811522e2a05d51f7
diff --git a/doc/tutorial/basics/rangedef.md b/doc/tutorial/basics/rangedef.md
index 7553558..038e96b 100644
--- a/doc/tutorial/basics/rangedef.md
+++ b/doc/tutorial/basics/rangedef.md
@@ -15,7 +15,7 @@
 uint8     >=0 & <=255
 int8      >=-128 & <=127
 uint16    >=0 & <=65536
-int16     >=-32_768 & <=.32_767
+int16     >=-32_768 & <=32_767
 rune      >=0 & <=0x10FFFF
 uint32    >=0 & <=4_294_967_296
 int32     >=-2_147_483_648 & <=2_147_483_647