Documentation/git-reflog: remove unneeded \ from \{

Documentation/git-reflog: remove unneeded \ from \{

There are some inconsistencies with how different asciidoc environments
handle different combinations of "\{<>}", e.g. these results were
observed with asciidoc on two different environments:

  | Input     | Output (env A) | Output (env B)   | same/different |
  |-----------+----------------+------------------+----------------|
  | \{<foo>\} | {&lt;foo&gt;}  | \{&lt;foo&gt;}^M | different      |
  | {<foo>}   | {&lt;foo&gt;}  | {&lt;foo&gt;}    | same           |
  | \{<foo>}  | {&lt;foo&gt;}  | \{&lt;foo&gt;}^M | different      |
  | \{foo\}   | {foo}          | {foo}            | same           |
  | \{\}      | {}             | \{}^M            | different      |
  | \{}       | {}             | {}               | same           |
  | {\}       | {}             | {}               | same           |

The only instance of this biting us is "@\{<specifier>\}" in
Documentation/git-reflog.txt; all other combinations of "\{<>}" (e.g. in
Documentation/revisions.txt) seem to render consistently.

Fix this inconsistent rendering by removing the unnecessary "\" in
Documentation/git-reflog.txt.

Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>