doc: software_maturity: Remove 20-connection limit from BLE support docs

SDC does not limit the number of connections to 20. Also, it is more
than just the central, observer, peripheral, and broadcaster roles
that can be used concurrently.

Signed-off-by: Olivier Lesage <[email protected]>

Author: olivier-le-sage

doc/nrf/releases_and_maturity/software_maturity.rst

@@ -949,7 +949,7 @@ The following table indicates the software maturity levels of the support for ea
              - --
              - --
 
-  | [1]: Concurrent central, observer, peripheral, and broadcaster roles with up to 20 concurrent connections along with one Observer and one Broadcaster (subject to RAM availability)
+  | [1]: Subject to RAM availability
   | [2]: Do not support encrypting and decrypting the Isochronous Channels packets
   | [3]: Only AoA transmitter is supported