Update configurations instructions in README.txt files to show ':' delimiter vs '/' delimiter.

README.txt

@@ -44,7 +44,7 @@ ways to do that:
    like:  make APPDIR=<path> or make CONFIG_APPS_DIR=<path>
 3) When you configure NuttX using tools/configure.sh, you can provide that
    path to the application directory on the configuration command line
-   like: ./configure.sh -a <app-dir> <board-name>/<config-name>
+   like: ./configure.sh -a <app-dir> <board-name>:<config-name>
 
 Built-In Applications
 ---------------------
@@ -216,7 +216,7 @@ A: Here are three:
         b) Add a symbolic link to MyApplication at apps/external
         c) Configure NuttX (usually by:
 
-           tools/configure.sh MyBoard/MyConfiguration
+           tools/configure.sh MyBoard:MyConfiguration
 
       Use of the name ''apps/external'' is suggested because that name
       is included in the .gitignore file and will save you some nuisance

graphics/nxwidgets/UnitTests/README.txt

@@ -46,8 +46,7 @@ Installing and Building the Unit Tests
 
      cd <nuttx-directory-path>
      make distclean
-     cd tools
+     tools/configure.sh sim:nsh2
-     ./configure.sh sim/nsh2
 
    Where:
 

graphics/traveler/tools/libwld/README.txt

@@ -5,7 +5,7 @@ Build instuctions:
   configurations (such as color format).
 
     1. cd nuttx/tools
-       ./configure.sh sim/traveler (for example)
+       ./configure.sh sim:traveler (for example)
     2. cd ..
        tools/sethost.sh -w or -l
        make context

graphics/traveler/tools/tcledit/README.txt

@@ -13,7 +13,7 @@ Build instuctions
   configurations (such as color format).
 
     1. cd nuttx/tools
-       ./configure.sh sim/traveler (for example)
+       ./configure.sh sim:traveler (for example)
     2. cd ..
        tools/sethost.sh -w or -l
        make context