Documentation: Escape <= characters in user-search.txt

Without escaping '<=' is rendered as ⇐ by AsciiDoc.

Change-Id: I2223cca45f80c2aaee76d1e84c2de34e966d7620
diff --git a/Documentation/user-search.txt b/Documentation/user-search.txt
index 55f668e..3b665af 100644
--- a/Documentation/user-search.txt
+++ b/Documentation/user-search.txt
@@ -453,7 +453,7 @@
 For example, added:>50 will be true for any change which adds at least 50
 lines.
 +
-Valid relations are >=, >, <=, <, or no relation, which will match if the
+Valid relations are >=, >, \<=, <, or no relation, which will match if the
 number of lines is exactly equal.
 
 [[commentby]]
@@ -505,7 +505,7 @@
 For example, unresolved:>0 will be true for any change which has at least one unresolved
 comment while unresolved:0 will be true for any change which has all comments resolved.
 +
-Valid relations are >=, >, <=, <, or no relation, which will match if the number of unresolved
+Valid relations are >=, >, \<=, <, or no relation, which will match if the number of unresolved
 comments is exactly equal.
 
 == Argument Quoting
@@ -622,7 +622,7 @@
 Matches changes with a +1 code review where the reviewer is in the
 ldap/linux.workflow group.
 
-`label:Code-Review<=-1`::
+`label:Code-Review\<=-1`::
 +
 Matches changes with either a -1, -2, or any lower score.