Merge pull request #1195 from AGlass0fMilk/add-debug-profile-note

Add debug build profile note

Author: Amanda Butler

docs/tools/CLI/build_profiles.md

@@ -18,6 +18,8 @@ Arm Mbed OS 5 defines three collections of toolchain flags used during the build
 - Easy to step through code with a debugger.
 - Disabled sleep mode.
 
+<span class="notes">**Note:** The debug profile uses optimization flags that may cause unwanted behavior during debugging (such as out-of-order jumps and optimized-out variables). If this occurs, you can set the compiler to the lowest possible optimization setting (for example, change `-Og` to `-O0` for GCC). See your toolchain's documentation for more information.</span>
+
 ## Release
 
 - Smallest code size and still fast.