Update the NuttX-STM32 documentation (#3986)

Fixed and updated some of the repository locations and the
relevant build commands.

- Updating `stlink` fixes a CMake build error on the 1.5.1 branch
- Updating the `kconfig` build command allows creating `kconfig-tweak`,
  which fixes a warning during the NuttX configuration

JerryScript-DCO-1.0-Signed-off-by: Mátyás Mustoha mmatyas@inf.u-szeged.hu

targets/nuttx-stm32f4/README.md

@@ -14,9 +14,9 @@ Clone the necessary projects into a `jerry-nuttx` directory. The last tested wor
 mkdir jerry-nuttx && cd jerry-nuttx
 
 git clone https://github.com/jerryscript-project/jerryscript.git
-git clone https://bitbucket.org/nuttx/nuttx.git -b release/9.0
-git clone https://bitbucket.org/nuttx/apps.git -b release/9.0
-git clone https://github.com/texane/stlink.git -b v1.5.1
+git clone https://bitbucket.org/nuttx/nuttx.git -b releases/9.0
+git clone https://bitbucket.org/nuttx/apps.git -b releases/9.0
+git clone https://github.com/texane/stlink.git -b v1.5.1-patch
 ```
 
 The following directory structure is created after these commands:
@@ -108,7 +108,6 @@ cd nuttx-tools/kconfig-frontends
     --disable-nconf \
     --disable-gconf \
     --disable-qconf \
-    --disable-utils \
     --disable-shared \
     --enable-static \
     --prefix=${PWD}/install