docs: Fix exposure cap getter of GSM

src/contracts/facilitators/gsm/interfaces/IGsm.sol

@@ -260,7 +260,7 @@ interface IGsm is IAccessControl, IGhoFacilitator {
   function getAvailableUnderlyingExposure() external view returns (uint256);
 
   /**
-   * @notice Returns the GSM exposure capacity
+   * @notice Returns the exposure limit to the underlying asset
    * @return The maximum amount of underlying asset that can be sold to the GSM
    */
   function getExposureCap() external view returns (uint128);