Documentation: Adding information of availability of RAM encryption and that in EFI mode we can't encrypt whole disk

doc/html/System Encryption.html

@@ -65,7 +65,8 @@ Because of BIOS requirement, the pre-boot password is typed using <strong>US key
 </strong>During the system encryption process, VeraCrypt automatically and transparently switches the keyboard to US layout in order to ensure that the password value typed will match the one typed in pre-boot mode. Thus, in order to avoid wrong password errors,
  one must type the password using the same keys as when creating the system encryption.</div>
 <p>Note: By default, Windows 7 and later boot from a special small partition. The partition contains files that are required to boot the system. Windows allows only applications that have administrator privileges to write to the partition (when the system is
- running). VeraCrypt encrypts the partition only if you choose to encrypt the whole system drive (as opposed to choosing to encrypt only the partition where Windows is installed).</p>
+ running). In EFI boot mode, which is the default on modern PCs, VeraCrypt can not encrypt this partition since it must remain unencrypted so that the BIOS can load the EFI bootloader from it. This in turn implies that in EFI boot mode, VeraCrypt offers only to encrypt the system partition where Windows is installed (the user can later manualy encrypt other data partitions using VeraCrypt). 
+ In MBR legacy boot mode, VeraCrypt encrypts the partition only if you choose to encrypt the whole system drive (as opposed to choosing to encrypt only the partition where Windows is installed).</p>
 <p>&nbsp;</p>
 <p><a href="Hidden%20Operating%20System.html" style="text-align:left; color:#0080c0; text-decoration:none; font-weight:bold.html">Next Section &gt;&gt;</a></p>
 </div>

doc/html/Unencrypted Data in RAM.html

@@ -48,6 +48,10 @@ Inherently, unencrypted master keys have to be stored in RAM too. When a non-sys
  cleanly restarted), or when the system crashes, <strong style="text-align:left">
 VeraCrypt naturally stops running and therefore cannot </strong>erase any keys or any other sensitive data. Furthermore, as Microsoft does not provide any appropriate API for handling hibernation and shutdown, master keys used for system encryption cannot be
  reliably (and are not) erased from RAM when the computer hibernates, is shut down or restarted.**</div>
+<div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
+Starting from version 1.24, VeraCrypt introduces a mechanism to encrypt master keys and cached passwords in RAM. This RAM encryption mechanism must be activated manually in "Performance/Driver Configuration" dialog. RAM encryption comes with a performance overhead (between 5% and 15% depending on the CPU speed) and it disables Windows hibernate. <br>
+Moreover, VeraCrypt 1.24 and above provide an additional security mechanism when system encryption is used that makes VeraCrypt erase master keys from RAM when a new device is connected to the PC. This additional mechanism can be activated using an option in System Settings dialog.<br/>
+Even though both above mechanisms provides strong protection for masterskeys and cached password, users should still take usual precautions related for the safery of sensitive data in RAM.</div>
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