Edit GattClient.md

Make minor edits, mostly for active voice.

Author: Amanda Butler

docs/api/bluetooth/GattClient.md

@@ -1,6 +1,6 @@
 ## GattClient
 
-Generic Attribute Profile (GATT) is used to discover services, characteristics and descriptors and to perform operations on them. The interaction happens between two peers, one of which is the client (who initiates interactions) and the other the server (which responds). Attribute Protocol (ATT) is used to implement this interaction. `GattClient` defines procedures required for interacting with a remote `GattServer`.
+You can use Generic Attribute Profile (GATT) to discover services, characteristics and descriptors and to perform operations on them. The interaction happens between two peers, one of which is the client (which initiates interactions) and the other is the server (which responds). You can use Attribute Protocol (ATT) to implement this interaction. `GattClient` defines procedures required for interacting with a remote `GattServer`.
 
 #### Discovery procedures
 
@@ -18,13 +18,13 @@ Mbed BLE abstracts read and write operations to offer a single API that can be u
 
 #### Attribute Protocol Maximum Transmission Unit (ATT_MTU)
 
-ATT_MTU is the maximum size of the attribute protocol packet. Operation on attributes too large to fit into a single packet will be split across multiple operations.
+`ATT_MTU` is the maximum size of the attribute protocol packet. Operation on attributes too large to fit into a single packet are split across multiple operations.
 
-This is independent of the Data Length which controls the over-the-air packet payload size (which is dealt with in the GAP). An L2CAP packet containing the attribute protocol packet will be fragmented over many such packets if required.
+This is independent of the data length, which controls the over-the-air packet payload size (which the GAP handles). An L2CAP packet containing the attribute protocol packet is fragmented over many packets if required.
 
-Only `GattClient` can trigger the exchange of ATT_MTU between client and server. Depending on the implementation of the bluetooth stack the client may trigger the exchange upon connection. The exchange may also be requested manually using `negotiateAttMtu`. If an exchange happens the biggest value possible across both devices will be used. Negotiation is only a best effort process and does not guarantee a higher value being set. 
+Only `GattClient` can trigger the exchange of `ATT_MTU` between client and server. Depending on the implementation of the bluetooth stack, the client may trigger the exchange upon connection. You may also manually request the exchange using `negotiateAttMtu`. If an exchange happens, the biggest value possible across both devices will be used. Negotiation is only a best-effort process and does not guarantee a higher value being set.
 
-ATT_MTU is at least 23 octets by default. If a larger size is negotiated the user application will be informed through the `onAttMtuChange` function called in the `GattClient::EventHandler` (`GattServer::EventHandler` will also be informed).
+`ATT_MTU` is at least 23 octets by default. If a larger size is negotiated, the user application will be informed through the `onAttMtuChange` function called in the `GattClient::EventHandler`. (`GattServer::EventHandler` is also informed.)
 
 #### Server initiated events