Remove instructures to CD to tools/ before running ./configure.sh

Squashed commit of the following:

    configs/*/README.txt: Replace each occurrence of './configure.sh' with 'tools/configure.sh'
    configs/*/README.txt:  Remove 'cd ..' after each './configure.sh'
    configs/*/README.txt:  Remove 'cd -' after each './configure.sh'
    configs/*/README.txt:  Remove 'cd tools' before each './configure.sh'
    configs/README.txt:  Remove instruction to CD tools/ before running configure.sh.

configs/cloudctrl/README.txt

@@ -468,9 +468,7 @@ Configurations
 Each Cloudctrl configuration is maintained in a sub-directory and
 can be selected as follow:
 
-    cd tools
-    ./configure.sh shenzhou/<subdir>
-    cd -
+    tools/configure.sh shenzhou/<subdir>
 
 Where <subdir> is one of the following:
 
@@ -545,14 +543,12 @@ Where <subdir> is one of the following:
 
     1. Intall the nxwm configuration
 
-       $ cd ~/nuttx-code/tools
-       $ ./configure.sh shenzhou/nxwm
+       $ cd ~/nuttx-code
+       $ tools/configure.sh shenzhou/nxwm
 
     2. Make the build context (only)
 
-       $ cd ..
        $ make context
-       ...
 
     3. Install the nxwm unit test