Improve Linux cmake getting started documentation

Closes https://github.com/espressif/esp-idf/pull/3347

docs/en/get-started-cmake/index.rst

@@ -283,7 +283,7 @@ Linux and MacOS
     cd ~/esp/hello_world
     idf.py menuconfig
 
-If your default version of Python is 3.x, you may need to run ``python2 idf.py`` instead.
+If your default version of Python is 3.x, you may need to run ``python2 $(which idf.py) menuconfig`` instead.
 
 Windows
 ~~~~~~~

docs/en/get-started-cmake/linux-setup.rst

@@ -21,7 +21,7 @@ To compile with ESP-IDF you need to get the following packages:
 
 - Arch::
 
-    sudo pacman -S --needed gcc git make ncurses flex bison gperf python2-pyserial python2-cryptography python2-future python2-pyparsing python2-pyelftools cmake ninja ccache
+    sudo pacman -S --needed gcc git make ncurses flex bison gperf python2-pip python2-pyserial python2-cryptography python2-future python2-pyparsing python2-pyelftools cmake ninja ccache
 
 .. note::
     CMake version 3.5 or newer is required for use with ESP-IDF. Older Linux distributions may require updating, enabling of a "backports" repository, or installing of a "cmake3" package rather than "cmake".