BUG/MINOR: peers: fix internal/network key type mapping.

Network types were directly and mistakenly mapped on sample types:

This patch fix the doc with values effectively used to keep backward
compatiblitiy on existing implementations.

In addition it adds an internal/network mapping for key types to avoid
further mistakes adding or modifying internals types.

This patch should be backported on all maintained branches,
particularly until v1.8 included for documentation part.
diff --git a/doc/peers-v2.0.txt b/doc/peers-v2.0.txt
index 477e7bb..344cb56 100644
--- a/doc/peers-v2.0.txt
+++ b/doc/peers-v2.0.txt
@@ -191,11 +191,11 @@
 
 Table Type present the numeric type of key used to store stick table entries:
 integer
- 0: signed integer
- 1: IPv4 address
- 2: IPv6 address
- 3: string
- 4: binary
+ 2: signed integer
+ 4: IPv4 address
+ 5: IPv6 address
+ 6: string
+ 7: binary
 
 Table Keylen present the key length or max length in case of strings or binary (padded with 0).