[docs] Remove "meta-class" term

Term "meta-class" could be understood in a wrong way due to different
meanings in Python and MuranoPL. So it is better to change it to
"metadata class", just "metadata" or just "class" where appropriate
across the documentation.

Change-Id: I6bec63f9268cb96c721ef419c5b53a80359eb9f8

doc/source/appdev-guide/murano_pl/metadata.rst

@@ -13,26 +13,29 @@ keyword for every new feature.
 
 Work with metadata includes the following cases:
 
-* Defining your own meta-classes
+* Defining your own metadata classes
 * Attaching metadata to various parts of MuranoPL code
 * Obtaining metadata and its usage
 
-Define meta-classes
--------------------
+Define metadata classes
+-----------------------
 
-Define meta-class with the description of arbitrary metadata. Meta-class and
-regular class have two differences. The ``Usage`` attribute of meta-class
-equals to ``Meta``, while the ``Usage`` attribute of regular class equals to
-``Class``. The default value of the ``Usage`` attribute is ``Class``.
-Meta-class also has additional attributes (``Cardinality``, ``Applies`` and
-``Inherited``) to control how and where instances of that meta-class can
-be attached.
+Define MuranoPL class with the description of arbitrary metadata. The class
+that can be used as metadata differs from the regular class:
+
+* The ``Usage`` attribute of the former equals to ``Meta``, while the ``Usage``
+  attribute of the latter equals to ``Class``. The default value of the
+  ``Usage`` attribute is ``Class``.
+
+* Metadata class has additional attributes (``Cardinality``, ``Applies`` and
+  ``Inherited``) to control how and where instances of that class can be
+  attached.
 
 Cardinality
 +++++++++++
 
 The ``Cardinality`` attribute can be set to either ``One`` or ``Many`` and
-indicates the possibility to attach two or more instances of meta-class to a
+indicates the possibility to attach two or more instances of metadata to a
 single language entity. The default value is ``One``.
 
 Applies
@@ -40,7 +43,7 @@ Applies
 
 The ``Applies`` attribute can be set to one of ``Package``, ``Type``,
 ``Method``, ``Property``, ``Argument`` or ``All`` and controls the possible
-language entities which instances of meta-class can be attached to. It is
+language entities which instances of metadata class can be attached to. It is
 possible to specify several values using YAML list notation. The default value
 is ``All``.
 
@@ -86,7 +89,7 @@ The following example shows a simple meta-class implementation:
         Contract: $.int().check($ >= 0)
         Default: 0
 
-``MetaClassOne`` is defined as a meta-class by setting the ``Usage``
+``MetaClassOne`` is defined as a metadata class by setting the ``Usage``
 attribute to ``Meta``. The ``Cardinality`` and ``Applies`` attributes determine
 that only one instance of ``MetaClassOne`` can be attached to object of any
 type. The ``Inherited`` attribute is omitted so there is no metadata
@@ -95,7 +98,7 @@ example above, ``Cardinality`` and ``Applies`` can be omitted as well, as
 their values are set to default but in this case the author wants to be
 explicit.
 
-The following example shows meta-class with different values of attributes:
+The following example shows metadata class with different values of attributes:
 
 .. code-block:: yaml
 
@@ -123,9 +126,9 @@ Attach metadata to a MuranoPL entity
 
 To attach metadata to MuranoPL class, package, property, method or method
 argument, add the ``Meta`` keyword to its description. Under the
-description, specify a list of meta-class instances which you want to attach
-to the entity. To attach only one meta-class instance, use a single scalar
-instead of a list.
+description, specify a list of metadata class instances which you want to
+attach to the entity. To attach only one metadata class instance, use a single
+scalar instead of a list.
 
 Consider the example of attaching previously defined metadata to different
 entities in a class definition:
@@ -177,8 +180,8 @@ entities in a class definition:
               - $._environment.reporter.report($this, 'Deploy finished')
               - $.setAttr(deployed, true)
 
-The ``Bar`` class has an instance of meta-class ``MetaClassOne`` attached. For
-this, the ``Meta`` keyword is added to the ``Bar`` class description and
+The ``Bar`` class has an instance of metadata class ``MetaClassOne`` attached.
+For this, the ``Meta`` keyword is added to the ``Bar`` class description and
 the instance of the ``MetaClassOne`` class is specified under it. This
 instance's properties are ``description`` and ``count``.
 
@@ -272,8 +275,7 @@ Capabilities can include version of software, information for use in UI or
 CLI, permissions, and any other. Metadata can also be used in requirements as
 a part of the contract.
 
-The following example demonstrates the possible use cases for the
-meta-classes:
+The following example demonstrates the possible use cases for the metadata:
 
 .. code-block:: yaml
 
@@ -302,15 +304,15 @@ meta-classes:
 Note, that the classes in the example do not exist as of Murano Mitaka, and
 therefore the example is not a real working code.
 
-The ``SomeFeatureSupport`` meta-class with ``support: true`` says that the
-``BlogApp`` application supports some feature. The ``Deprecated`` meta-class
+The ``SomeFeatureSupport`` metadata with ``support: true`` says that the
+``BlogApp`` application supports some feature. The ``Deprecated`` metadata
 attached to the ``volumeName`` property informs that this
 property has a better alternative and it will not be used in the future
-versions anymore. The ``CallerMustBeAdmin`` meta-class attached to the
+versions anymore. The ``CallerMustBeAdmin`` metadata attached to the
 ``importantAction`` method sets permission to execute this method to the
 admin users only.
 
 In the contract of the ``server`` property it is specified that the server
 application must be of the ``srv:CoolServer`` class and must have the
-attached meta-object of the ``m:SomeFeatureSupport`` meta-class with the
+attached meta-object of the ``m:SomeFeatureSupport`` class with the
 ``support`` property set to ``true``.