Better documentation for npm, pecl, and pip states

This commit adds additional info to the top docstring for these states,
including SLS examples for how to properly set up requisites to ensure
that npm/pecl/pip is installed before these states are run.

salt/states/npm.py

@@ -1,5 +1,21 @@
 '''
-A state module to manage installed NPM packages.
+Installation of NPM Packages
+============================
+
+These states manage the installed packages for node.js using the Node Package
+Manager (npm). Note that npm must be installed for these states to be
+available, so npm states should include a requisite to a pkg.installed state
+for the package which provides npm (simply ``npm`` in most cases). Example:
+
+.. code-block:: yaml
+
+    npm:
+      pkg.installed
+
+    yaml:
+      npm.installed:
+        - require:
+          - pkg: npm
 '''
 
 # Import salt libs

salt/states/pecl.py

@@ -1,13 +1,21 @@
 '''
-Installation of PHP pecl extensions.
-==============================================
+Installation of PHP Extensions Using pecl
+=========================================
 
-A state module to manage php pecl extensions.
+These states manage the installed pecl extensions. Note that php-pear must be
+installed for these states to be available, so pecl states should include a
+requisite to a pkg.installed state for the package which provides pecl
+(``php-pear`` in most cases). Example:
 
 .. code-block:: yaml
 
+    php-pear:
+      pkg.installed
+
     mongo:
-      pecl.installed
+      pecl.installed:
+        - require:
+          - pkg: php-pear
 '''
 
 

salt/states/pip.py

@@ -1,13 +1,21 @@
 '''
-Installation of Python packages using pip.
-==========================================
+Installation of Python Packages Using pip
+=========================================
 
-A state module to manage system installed python packages
+These states manage system installed python packages. Note that pip must be
+installed for these states to be available, so pip states should include a
+requisite to a pkg.installed state for the package which provides pip
+(``python-pip`` in most cases). Example:
 
 .. code-block:: yaml
 
+    python-pip:
+      pkg.installed
+
     virtualenvwrapper:
-      pip.installed
+      pip.installed:
+        - require:
+          - pkg: python-pip
 '''
 
 import urlparse