[doc] import_role: mention version from which behavior changed and fix some typos (#43843)

* [doc] fix some typos

* [doc] import_role: mention version from which behavior changed

docs/docsite/rst/porting_guides/porting_guide_2.7.rst

@@ -31,7 +31,7 @@ include_role and import_role variable exposure
 
 In Ansible 2.7 a new module argument named ``public`` was added to the ``include_role`` module that dictates whether or not the role's ``defaults`` and ``vars`` will be exposed outside of the role, allowing those variables to be used by later tasks.  This value defaults to ``public: False``, matching current behavior.
 
-``import_role`` does not support the ``public`` argument, and will unconditionally expose the role's ``defaults`` and ``vars`` to the rest of the playbook. This functinality brings ``import_role`` into closer alignment with roles listed within the ``roles`` header in a play.
+``import_role`` does not support the ``public`` argument, and will unconditionally expose the role's ``defaults`` and ``vars`` to the rest of the playbook. This functionality brings ``import_role`` into closer alignment with roles listed within the ``roles`` header in a play.
 
 There is an important difference in the way that ``include_role`` (dynamic) will expose the role's variables, as opposed to ``import_role`` (static). ``import_role`` is a pre-processor, and the ``defaults`` and ``vars`` are evaluated at playbook parsing, making the variables available to tasks and roles listed at any point in the play. ``include_role`` is a conditional task, and the ``defaults`` and ``vars`` are evaluated at execution time, making the variables available to tasks and roles listed *after* the ``include_role`` task.
 

lib/ansible/modules/utilities/logic/import_role.py

@@ -56,8 +56,9 @@ options:
     default: 'no'
 notes:
   - Handlers are made available to the whole play.
-  - Variables defined in C(vars) and C(default) for the role are exposed at playbook parsing time. Due to this,
-    these variables will be accessible to roles and tasks executed before the the location of the C(import_role) task.
+  - "Since Ansible 2.7: variables defined in C(vars) and C(defaults) for the role are exposed at playbook parsing time.
+    Due to this, these variables will be accessible to roles and tasks executed before the location of the
+    C(import_role) task."
   - Unlike C(include_role) variable exposure is not configurable, and will always be exposed.
 '''