Added conditional headers to HEAD request documentation

Currently, conditional headers, e.g. If-Match, If-Modified-Since, etc.,
are listed for the GET objects API call, but not in the HEAD objects
call in the api-ref documentation.  This patch adds the missing headers
to the HEAD documentation.

Change-Id: Idd1c248cc27415d148a1b9a5eb2e95f25b8c4da0
Closes-Bug: #1630212

api-ref/source/parameters.yaml

@@ -196,7 +196,18 @@ If-Modified-Since:
   in: header
   required: false
   type: string
-If-None-Match:
+If-None-Match-get-request:
+  description: |
+    A client that has one or more entities previously
+    obtained from the resource can verify that none of those entities is
+    current by including a list of their associated entity tags in the
+    ``If-None-Match header`` field.
+    See `Request for Comments: 2616 <http://www.ietf.org/rfc/rfc2616.txt>`_
+    for details.
+  in: header
+  required: false
+  type: string
+If-None-Match-put-request:
   description: |
     In combination with ``Expect: 100-Continue``,
     specify an ``"If-None-Match: *"`` header to query whether the

api-ref/source/storage-object-services.inc

@@ -113,7 +113,7 @@ Request
    - multipart-manifest: multipart-manifest_get
    - Range: Range
    - If-Match: If-Match
-   - If-None-Match: If-None-Match
+   - If-None-Match: If-None-Match-get-request
    - If-Modified-Since: If-Modified-Since
    - If-Unmodified-Since: If-Unmodified-Since
    - X-Trans-Id-Extra: X-Trans-Id-Extra
@@ -255,7 +255,7 @@ Request
    - X-Delete-At: X-Delete-At
    - X-Delete-After: X-Delete-After
    - X-Object-Meta-name: X-Object-Meta-name
-   - If-None-Match: If-None-Match
+   - If-None-Match: If-None-Match-put-request
    - X-Trans-Id-Extra: X-Trans-Id-Extra
 
 
@@ -565,6 +565,10 @@ Request
    - filename: filename
    - multipart-manifest: multipart-manifest_head
    - X-Newest: X-Newest
+   - If-Match: If-Match
+   - If-None-Match: If-None-Match-get-request
+   - If-Modified-Since: If-Modified-Since
+   - If-Unmodified-Since: If-Unmodified-Since
    - X-Trans-Id-Extra: X-Trans-Id-Extra