Put appropriate module attributes into doc fragments.

plugins/doc_fragments/module_certificate.py

@@ -16,6 +16,9 @@ class ModuleDocFragment(object):
 description:
   - This module allows one to (re)generate OpenSSL certificates.
   - It uses the cryptography python library to interact with OpenSSL.
+attributes:
+  diff_mode:
+    support: full
 requirements:
   - cryptography >= 1.6 (if using V(selfsigned) or V(ownca) provider)
 options:

plugins/doc_fragments/module_csr.py

@@ -15,6 +15,9 @@ class ModuleDocFragment(object):
 description:
   - This module allows one to (re)generate OpenSSL certificate signing requests.
   - This module supports the subjectAltName, keyUsage, extendedKeyUsage, basicConstraints and OCSP Must Staple extensions.
+attributes:
+  diff_mode:
+    support: full
 requirements:
   - cryptography >= 1.3
 options:

plugins/doc_fragments/module_privatekey.py

@@ -17,6 +17,9 @@ description:
     L(ECC,https://en.wikipedia.org/wiki/Elliptic-curve_cryptography) or L(EdDSA,https://en.wikipedia.org/wiki/EdDSA) private
     keys.
   - Keys are generated in PEM format.
+attributes:
+  diff_mode:
+    support: full
 requirements:
   - cryptography >= 1.2.3 (older versions might work as well)
 options:

plugins/doc_fragments/module_privatekey_convert.py

@@ -14,6 +14,9 @@ class ModuleDocFragment(object):
     DOCUMENTATION = r"""
 requirements:
   - cryptography >= 1.2.3 (older versions might work as well)
+attributes:
+  diff_mode:
+    support: none
 options:
   src_path:
     description:

plugins/modules/openssl_csr.py

@@ -27,8 +27,6 @@ extends_documentation_fragment:
 attributes:
   check_mode:
     support: full
-  diff_mode:
-    support: full
   safe_file_operations:
     support: full
 options:

plugins/modules/openssl_csr_pipe.py

@@ -31,8 +31,6 @@ attributes:
         in community.crypto 3.0.0.
       - From community.crypto 3.0.0 on, the module will ignore check mode and always behave as if check mode is not active.
         If you think this breaks your use-case of this module, please create an issue in the community.crypto repository.
-  diff_mode:
-    support: full
 options:
   content:
     description:

plugins/modules/openssl_privatekey.py

@@ -29,8 +29,6 @@ extends_documentation_fragment:
 attributes:
   check_mode:
     support: full
-  diff_mode:
-    support: full
   safe_file_operations:
     support: full
 options:

plugins/modules/openssl_privatekey_convert.py

@@ -26,8 +26,6 @@ extends_documentation_fragment:
 attributes:
   check_mode:
     support: full
-  diff_mode:
-    support: none
   safe_file_operations:
     support: full
 options:

plugins/modules/openssl_privatekey_pipe.py

@@ -41,8 +41,6 @@ attributes:
         in community.crypto 3.0.0.
       - From community.crypto 3.0.0 on, the module will ignore check mode and always behave as if check mode is not active.
         If you think this breaks your use-case of this module, please create an issue in the community.crypto repository.
-  diff_mode:
-    support: full
 options:
   content:
     description:

plugins/modules/x509_certificate.py

@@ -38,8 +38,6 @@ extends_documentation_fragment:
 attributes:
   check_mode:
     support: full
-  diff_mode:
-    support: full
   safe_file_operations:
     support: full
 options:

plugins/modules/x509_certificate_pipe.py

@@ -35,8 +35,6 @@ attributes:
         in community.crypto 3.0.0.
       - From community.crypto 3.0.0 on, the module will ignore check mode and always behave as if check mode is not active.
         If you think this breaks your use-case of this module, please create an issue in the community.crypto repository.
-  diff_mode:
-    support: full
 options:
   provider:
     description: