Remove references to non-existent kostest from README.txt

configs/stm32f746g-disco/README.txt

@@ -527,85 +527,6 @@ Configurations
 Configuration Directories
 -------------------------
 
-  kostest:
-  -------
-    This is identical to the nsh configuration below except that NuttX is
-    built as a kernel-mode, monolithic module and the user applications are
-    built separately.  Is is recommended to use a special make command;
-    not just 'make' but make with the following two arguments:
-
-        make pass1 pass2
-
-    In the normal case (just 'make'), make will attempt to build both user-
-    and kernel-mode blobs more or less interleaved.  This actual works!
-    However, for me it is very confusing so I prefer the above make command:
-    Make the user-space binaries first (pass1), then make the kernel-space
-    binaries (pass2)
-
-    NOTES:
-
-    1. At the end of the build, there will be several files in the top-level
-       NuttX build directory:
-
-       PASS1:
-         nuttx_user.elf    - The pass1 user-space ELF file
-         nuttx_user.hex    - The pass1 Intel HEX format file (selected in defconfig)
-         User.map          - Symbols in the user-space ELF file
-
-       PASS2:
-         nuttx             - The pass2 kernel-space ELF file
-         nuttx.hex         - The pass2 Intel HEX file (selected in defconfig)
-         System.map        - Symbols in the kernel-space ELF file
-
-    2. Combining .hex files.  If you plan to use the STM32 ST-Link Utility to
-       load the .hex files into FLASH, then you need to combine the two hex
-       files into a single .hex file.  Here is how you can do that.
-
-       a. The 'tail' of the nuttx.hex file should look something like this
-          (with my comments added):
-
-            $ tail nuttx.hex
-            # 00, data records
-            ...
-            :10 9DC0 00 01000000000800006400020100001F0004
-            :10 9DD0 00 3B005A0078009700B500D400F300110151
-            :08 9DE0 00 30014E016D0100008D
-            # 05, Start Linear Address Record
-            :04 0000 05 0800 0419 D2
-            # 01, End Of File record
-            :00 0000 01 FF
-
-          Use an editor such as vi to remove the 05 and 01 records.
-
-       b. The 'head' of the nuttx_user.hex file should look something like
-          this (again with my comments added):
-
-            $ head nuttx_user.hex
-            # 04, Extended Linear Address Record
-            :02 0000 04 0801 F1
-            # 00, data records
-            :10 8000 00 BD89 01084C800108C8110208D01102087E
-            :10 8010 00 0010 00201C1000201C1000203C16002026
-            :10 8020 00 4D80 01085D80010869800108ED83010829
-            ...
-
-          Nothing needs to be done here.  The nuttx_user.hex file should
-          be fine.
-
-       c. Combine the edited nuttx.hex and un-edited nuttx_user.hex
-          file to produce a single combined hex file:
-
-          $ cat nuttx.hex nuttx_user.hex >combined.hex
-
-       Then use the combined.hex file with the STM32 ST-Link tool.  The
-       mbed interface does not seem to except .hex files, but you can
-       also convert the .hex file to binary with this command:
-
-         arm-none-eabi-objcopy.exe -I ihex -O binary combined.hex combined.bin
-
-       If you do this a lot, you will probably want to invest a little time
-       to develop a tool to automate these steps.
-
   nsh:
   ---
     Configures the NuttShell (NSH) located at apps/examples/nsh.  The