Adjust backticks to preserve markdown format

Escapes the `<<` symbol, preventing it from triggering
Markdown (probably html in this case) formatting/highlighting in some
viewers.

Change-Id: Ic1f81a65da1fcc7e542652609fc98502fcfc6380

docs/kelvin_isa.md

diff --git a/docs/kelvin_isa.md b/docs/kelvin_isa.md
index 33cbf66..a623ffb 100644
--- a/docs/kelvin_isa.md
+++ b/docs/kelvin_isa.md
@@ -293,14 +293,14 @@
 
 ### Exit Cause
 
-*   enum_IDLE = 0
-*   enum_EBREAK = 1
-*   enum_ECALL = 2
-*   enum_EEXIT = 3
-*   enum_EYIELD = 4
-*   enum_ECTXSW = 5
-*   enum_UNDEF_INST = (1u<<31) | 2
-*   enum_USAGE_FAULT = (1u<<31) | 16
+*   `enum_IDLE = 0`
+*   `enum_EBREAK = 1`
+*   `enum_ECALL = 2`
+*   `enum_EEXIT = 3`
+*   `enum_EYIELD = 4`
+*   `enum_ECTXSW = 5`
+*   `enum_UNDEF_INST = (1u<<31) | 2`
+*   `enum_USAGE_FAULT = (1u<<31) | 16`
 
 ## Instruction Definitions