Add TFTP detail to README.

Author: tintoy

README.md

@@ -30,7 +30,7 @@ ipxe:
   boot_script: "http://192.168.220.10:4777/?profile=development"
 ```
 
-* `boot_image` is the name of the initial iPXE boot image file sent to regular PXE clients.  
+* `boot_image` is the name of the initial iPXE boot image file (relative to `/var/lib/tftpboot`) sent to regular PXE clients.  
 PXE clients will load this image via TFTP (from the server where `mcp2-dhcp-server` is running).  
 When they load this image, iPXE will send a second discovery packet with a user class of `iPXE`.
 * `boot_script` is the URL of the iPXE script (HTTP or TFTP) sent to iPXE clients.
@@ -100,7 +100,7 @@ coreos:
 
 ### Process
 
-1. Create a VM using VMWare Workstation or VMWare fusion (ensure it has 1 disk and 1 network adapter, with hardware versiom <= 10).
+1. Create a VM using VMWare Workstation or VMWare fusion (ensure it has 1 disk and 1 network adapter, with hardware version <= 10).
 2. Do not install an operating system (leave the disk completely empty).
 3. Close VMWare, and use [ovftool](https://my.vmware.com/web/vmware/details?downloadGroup=OVFTOOL400&productId=353) to convert the virtual machine to OVF format (`ovftool myserver.vmx ovf/myserver.ovf`).
 4. Upload the `.ovf`, `.vmdk`, and `.mf` files to CloudControl and import it as a client image (ensure that "Import without Guest OS Customization" is checked, see [here](https://docs.mcp-services.net/display/CCD/How+to+Import+an+OVF+Package+as+a+Client+Image) for details).