githooks: use {old,new}-oid instead of {old,new}-value

Similar to the previous commit, rename {old,new}-value in the 'githooks'
documentation to {old,new}-oid. This improves clarity and also ensures
consistency within the document.

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/githooks.txt

@@ -275,12 +275,12 @@ This hook executes once for the receive operation. It takes no
 arguments, but for each ref to be updated it receives on standard
 input a line of the format:
 
-  <old-value> SP <new-value> SP <ref-name> LF
+  <old-oid> SP <new-oid> SP <ref-name> LF
 
-where `<old-value>` is the old object name stored in the ref,
-`<new-value>` is the new object name to be stored in the ref and
+where `<old-oid>` is the old object name stored in the ref,
+`<new-oid>` is the new object name to be stored in the ref and
 `<ref-name>` is the full name of the ref.
-When creating a new ref, `<old-value>` is the all-zeroes object name.
+When creating a new ref, `<old-oid>` is the all-zeroes object name.
 
 If the hook exits with non-zero status, none of the refs will be
 updated. If the hook exits with zero, updating of individual refs can
@@ -503,13 +503,13 @@ given reference transaction is in:
 For each reference update that was added to the transaction, the hook
 receives on standard input a line of the format:
 
-  <old-value> SP <new-value> SP <ref-name> LF
+  <old-oid> SP <new-oid> SP <ref-name> LF
 
-where `<old-value>` is the old object name passed into the reference
-transaction, `<new-value>` is the new object name to be stored in the
+where `<old-oid>` is the old object name passed into the reference
+transaction, `<new-oid>` is the new object name to be stored in the
 ref and `<ref-name>` is the full name of the ref. When force updating
 the reference regardless of its current value or when the reference is
-to be created anew, `<old-value>` is the all-zeroes object name. To
+to be created anew, `<old-oid>` is the all-zeroes object name. To
 distinguish these cases, you can inspect the current value of
 `<ref-name>` via `git rev-parse`.