localmodconfig: Document localmodconfig in README

Someone (over a year ago :-p) asked me to document localmodconfig in the
README file in the source code.  I thought it was a good idea but other
things were more important and I simply forgot about it.  Well, I
stumbled on the email asking me about this and I'm sending it out now.
Signed-off-by: NSteven "Mr. Procrastinator" Rostedt <rostedt@goodmis.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

README

@@ -206,6 +206,24 @@ CONFIGURING the kernel:
      "make randconfig"  Create a ./.config file by setting symbol
                         values to random values.
 
+     "make localmodconfig" Create a config based on current config and
+                           loaded modules (lsmod). Disables any module
+                           option that is not needed for the loaded modules.
+
+                           To create a localmodconfig for another machine,
+                           store the lsmod of that machine into a file
+                           and pass it in as a LSMOD parameter.
+
+                   target$ lsmod > /tmp/mylsmod
+                   target$ scp /tmp/mylsmod host:/tmp
+
+                   host$ make LSMOD=/tmp/mylsmod localmodconfig
+
+                           The above also works when cross compiling.
+
+     "make localyesconfig" Similar to localmodconfig, except it will convert
+                           all module options to built in (=y) options.
+
    You can find more information on using the Linux kernel config tools
    in Documentation/kbuild/kconfig.txt.