reorder the primitives list and improve a few titles (#3640)

diff --git a/docs/hazmat/primitives/cryptographic-hashes.rst b/docs/hazmat/primitives/cryptographic-hashes.rst
index 55af21a..521ae09 100644
--- a/docs/hazmat/primitives/cryptographic-hashes.rst
+++ b/docs/hazmat/primitives/cryptographic-hashes.rst
@@ -1,7 +1,7 @@
 .. hazmat::
 
-Message digests
-===============
+Message digests (Hashing)
+=========================
 
 .. module:: cryptography.hazmat.primitives.hashes
 
diff --git a/docs/hazmat/primitives/index.rst b/docs/hazmat/primitives/index.rst
index 022cb9f..78beb3d 100644
--- a/docs/hazmat/primitives/index.rst
+++ b/docs/hazmat/primitives/index.rst
@@ -6,12 +6,12 @@
 .. toctree::
     :maxdepth: 1
 
-    cryptographic-hashes
-    mac/index
-    symmetric-encryption
-    padding
-    key-derivation-functions
-    keywrap
     asymmetric/index
     constant-time
+    key-derivation-functions
+    keywrap
+    mac/index
+    cryptographic-hashes
+    symmetric-encryption
+    padding
     twofactor
diff --git a/docs/hazmat/primitives/padding.rst b/docs/hazmat/primitives/padding.rst
index 916b9bc..45bcc13 100644
--- a/docs/hazmat/primitives/padding.rst
+++ b/docs/hazmat/primitives/padding.rst
@@ -1,7 +1,7 @@
 .. hazmat::
 
-Padding
-=======
+Symmetric Padding
+=================
 
 .. module:: cryptography.hazmat.primitives.padding