(maint) Exclude files that cause YARD errors

Running `puppet strings server` generates documentation for all
modules in your modulepath, meaning that it also generates HTML
for strings itself. Since there are parts of strings that are not
meant to be documented with YARD, exclude the files that cause
error messages so that `puppet strings server` is not needlessly
noisy.

Additionally, make a few suggested changes to the README to make
it clearer and easier to read.

.yardopts

@@ -1 +1,2 @@
---exclude lib/puppetx/yardoc/yard/templates
+--exclude lib/puppetx/puppetlabs/strings/yard/templates/
+--exclude lib/puppetx/puppetlabs/strings/yard/code_objects/host_class_object.rb

README.md

@@ -43,11 +43,11 @@ documentation for all your modules using the `server` action:
 
 Writing Compatible Documentation
 -----
-Since the strings module is built around YARD, a few different comment formats are compatible.
+Since the strings module is built around YARD, a few different comment formats can be used.
 YARD can work with RDoc, meaning it is backwards compatible with previously documented modules.
-However, we would ultimately like to move away from RDoc use Markdown instead. You can configure
-which you would like YARD to use by adding a `.yardopts` file to the root of your module directory
-which specifies the desired format:
+Feel free to try out strings with RDoc, but we are planning to move to Markdown as the standard.
+You can configure which you would like YARD to use by adding a `.yardopts` file to the root of
+your module directory which specifies the desired format:
 
     --markup markdown
 
@@ -64,8 +64,6 @@ Here's an example of how you might document a 4x function:
      # @example using two integers
      #   $bigger_int = max(int_one, int_two)
      #
-     # See further documentation somewhere else
-     #
      # @return [Integer] the larger of the two parameters
      #
      # @param num_a [Integer] the first number to be compared
@@ -84,7 +82,8 @@ And here's an example of how you might document a class:
      # want to document a manifest in a way that is compatible.
      # with the strings module
      #
-     # @example { "example": }
+     # @example when declaring the example class
+     #   include example
      #
      # @param first_arg The first parameter for this class
      # @param second_arg The second paramter for this class