Correct the explanation for signcerts in Membership section

Signed-off-by: Manindra Singh <manindra23@yahoo.co.in>
(cherry picked from commit 5a372b9)

docs/source/membership/membership.md

@@ -172,9 +172,9 @@ A local MSP folder contains the following sub-folders:
 
   **Note:** If you are using a [Hardware Security Module(HSM)](../hsm.html) for key management, this folder is empty because the private key is generated by and stored in the HSM.
 
-* **signcert:** For a peer or orderer node (or in a client's local MSP) this folder contains the node's **signing key**. This key matches cryptographically the node's identity included in **Node Identity** folder and is used to sign data --- for example to sign a transaction proposal response, as part of the endorsement phase.
+* **signcert:**  For a peer or orderer node (or in a client’s local MSP) this folder contains the node’s certificate issued by CA. The certificate represents the node's identity, and this certificate's corresponding **private key** can be used to generate signatures which may be verified by anyone with a copy of this certificate.
 
-  This folder is mandatory for local MSPs, and must contain exactly one public key. Obviously, access to this folder must be limited only to the identities of users who have  administrative responsibility on the peer.
+  This folder is mandatory for local MSPs, and must contain exactly one **public key**. Obviously, access to this folder must be limited only to the identities of users who have administrative responsibility on the peer.
 
   Configuration of a **channel MSP** does not include this folder, as channel MSPs solely aim to offer identity validation functionalities and not signing abilities.