Merge pull request #536 from adamjstewart/fixes/doc_typos

Documentation typo fixes

lib/spack/docs/index.rst

@@ -18,7 +18,7 @@ configurations can coexist on the same system.
 Most importantly, Spack is *simple*.  It offers a simple *spec* syntax
 so that users can specify versions and configuration options
 concisely.  Spack is also simple for package authors: package files
-are writtin in pure Python, and specs allow package authors to
+are written in pure Python, and specs allow package authors to
 maintain a single file for many different builds of the same package.
 
 See the :doc:`features` for examples and highlights.

lib/spack/docs/packaging_guide.rst

@@ -419,7 +419,7 @@ directory to the directory containing the downloaded archive before it
 calls your ``install`` method.  Within ``install``, the path to the
 downloaded archive is available as ``self.stage.archive_file``.
 
-Here is an example snippet for packages distribuetd as self-extracting
+Here is an example snippet for packages distributed as self-extracting
 archives.  The example sets permissions on the downloaded file to make
 it executable, then runs it with some arguments.
 
@@ -1556,12 +1556,12 @@ you ask for a particular spec.
 ``Concretization Policies``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-A user may have certain perferrences for how packages should
+A user may have certain preferences for how packages should
 be concretized on their system.  For example, one user may prefer packages
 built with OpenMPI and the Intel compiler.  Another user may prefer
 packages be built with MVAPICH and GCC.  
 
-Spack can be configurated to prefer certain compilers, package
+Spack can be configured to prefer certain compilers, package
 versions, depends_on, and variants during concretization.
 The preferred configuration can be controlled via the 
 ``~/.spack/packages.yaml`` file for user configuations, or the
@@ -1588,16 +1588,16 @@ At a high level, this example is specifying how packages should be
 concretized.  The dyninst package should prefer using gcc 4.9 and 
 be built with debug options.  The gperftools package should prefer version
 2.2 over 2.4.  Every package on the system should prefer mvapich for
-its MPI and gcc 4.4.7 (except for Dyninst, which overrides this by perfering gcc 4.9).  
+its MPI and gcc 4.4.7 (except for Dyninst, which overrides this by preferring gcc 4.9).  
 These options are used to fill in implicit defaults.  Any of them can be overwritten 
 on the command line if explicitly requested.
 
-Each packages.yaml file begin with the string ``packages:`` and 
+Each packages.yaml file begins with the string ``packages:`` and 
 package names are specified on the next level. The special string ``all``
 applies settings to each package. Underneath each package name is 
 one or more components: ``compiler``, ``variants``, ``version``, 
 or ``providers``.  Each component has an ordered list of spec 
-``constraints``, with earlier entries in the list being prefered over
+``constraints``, with earlier entries in the list being preferred over
 later entries.
 
 Sometimes a package installation may have constraints that forbid