documentation: Scrubbed use of directory names

There was inconsistent use of the way directory names were
handled throughout the YP documentation.  I have scrubbed the
set and replaced many instances such as the following:

meta/<something> replaces /meta/<something>
poky replaces ~/poky (except in some very specific examples)

I basically got rid of leading slash characters.

Reported-by: Robert P. J. Day <rpjday@crashcourse.ca>
(From yocto-docs rev: ae2e451ed8f61484d04b30017021912c4493a441)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/kernel-dev/kernel-dev-maint-appx.xml

@@ -45,7 +45,7 @@
             Here is an example that assumes the local Git repository for the kernel is in
             a top-level directory named <filename>linux-yocto-3.4</filename>:
             <literallayout class='monospaced'>
-     $ cd ~/linux-yocto-3.4
+     $ cd linux-yocto-3.4
      $ git checkout -b meta origin/meta
             </literallayout>
             Once you have checked out and switched to the <filename>meta</filename> branch,
@@ -208,7 +208,7 @@
             the build tree directory.
             The files include the final <filename>.config</filename> file, all the <filename>.o</filename>
             files, the <filename>.a</filename> files, and so forth.
-            Since each machine or BSP has its own separate 
+            Since each machine or BSP has its own separate
             <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
             in its own separate branch
             of the Git repository, you can easily switch between different builds.