Add documentation to ExampleConditions

src/spectator/example_conditions.cr

@@ -1,5 +1,13 @@
 module Spectator
+  # Collection of checks that run before and after tests.
+  # The pre-conditions can be used to verify
+  # that the SUT is in an expected state prior to testing.
+  # The post-conditions can be used to verify
+  # that the SUT is in an expected state after tests have finished.
+  # Each check is just a `Proc` (code block) that runs when invoked.
   class ExampleConditions
+    # Creates an empty set of conditions.
+    # This will effectively run nothing extra while running a test.
     def self.empty
       new(
         [] of ->,
@@ -7,16 +15,21 @@ module Spectator
       )
     end
 
+    # Creates a new set of conditions.
     def initialize(
       @pre_conditions : Array(->),
       @post_conditions : Array(->)
     )
     end
 
+    # Runs all pre-condition checks.
+    # These should be run before every test.
     def run_pre_conditions
       @pre_conditions.each &.call
     end
 
+    # Runs all post-condition checks.
+    # These should be run after every test.
     def run_post_conditions
       @post_conditions.each &.call
     end