docs/*-setup: Use --enable-local instead of --prefix=$PWD for ct-ng

docs/linux-setup.rst

@@ -77,14 +77,16 @@ If you can't think of a reason why you need to build it yourself, then probably
 
 In any case, here are the steps to compile the toolchain yourself.
 
+(Note: You will also need the prerequisite packages mentioned in step 0, above.)
+
 - Install dependencies:
 
-  - Ubuntu::
+  - Ubuntu pre-16.04::
 
         sudo apt-get install gawk gperf grep gettext libncurses-dev python python-dev automake bison flex texinfo help2man libtool
 
   - Ubuntu 16.04::
-  
+
         sudo apt-get install gawk gperf grep gettext python python-dev automake bison flex texinfo help2man libtool libtool-bin
 
   - Debian::
@@ -100,7 +102,7 @@ Download ``crosstool-NG`` and build it::
     cd ~/esp
     git clone -b xtensa-1.22.x https://github.com/espressif/crosstool-NG.git
     cd crosstool-NG
-    ./bootstrap && ./configure --prefix=$PWD && make install
+    ./bootstrap && ./configure --enable-local && make install
 
 Build the toolchain::
 

docs/macos-setup.rst

@@ -89,7 +89,7 @@ Download ``crosstool-NG`` and build it::
     cd ~/esp
     git clone -b xtensa-1.22.x https://github.com/espressif/crosstool-NG.git
     cd crosstool-NG
-    ./bootstrap && ./configure --prefix=$PWD && make install
+    ./bootstrap && ./configure --enable-local && make install
 
 Build the toolchain::