docs: update README about IEEE802154 and 6LoWPAN

Signed-off-by: Thibaut Vandervelden <thvdveld@vub.be>

README.md

@@ -38,9 +38,8 @@ There are 3 supported mediums.
   * Jumbo frames are **not** supported.
 * IP
   * Unicast, broadcast and multicast packets are supported.
-* IEEE 802.15.4 + 6LoWPAN (experimental)
-  * Unicast, broadcast and multicast packets are supported.
-  * ONLY UDP packets are supported.
+* IEEE 802.15.4
+  * Only support for data frames.
 
 ### IP layer
 
@@ -62,6 +61,14 @@ There are 3 supported mediums.
   * ICMPv6 parameter problem message is **not** generated in response to an unknown IPv6
     hop-by-hop option.
 
+#### 6LoWPAN
+  
+  * Implementation of [RFC6282](https://tools.ietf.org/rfc/rfc6282.txt).
+  * Fragmentation is supported, as defined in [RFC4944](https://tools.ietf.org/rfc/rfc4944.txt).
+  * UDP header compression is supported.
+  * Extension header compression is **not** supported (will be soon™).
+  * Uncompressed IP headers are supported.
+
 ### IP multicast
 
 #### IGMP
@@ -204,12 +211,13 @@ Enable the corresponding socket type.
 
 These features are enabled by default.
 
-### Features `proto-ipv4` and `proto-ipv6`
+### Features `proto-ipv4`, `proto-ipv6` and `proto-sixlowpan`
 
-Enable [IPv4] and [IPv6] respectively.
+Enable [IPv4], [IPv6] and [6LoWPAN] respectively.
 
 [IPv4]: https://tools.ietf.org/rfc/rfc791.txt
 [IPv6]: https://tools.ietf.org/rfc/rfc8200.txt
+[6LoWPAN]: https://tools.ietf.org/rfc/rfc6282.txt
 
 ## Configuration