fix typo in reference_guide.md

Author: shubhe25p

docs/reference_guide.md

@@ -1535,7 +1535,7 @@ Check the [BPF helpers reference](kernel-versions.md#helpers) to see which helpe
 
 ## Rewriter
 
-One of jobs for rewriter is to turn implicit memory accesses to explicit ones using kernel helpers. Recent kernel introduced a config option ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE which will be set for architectures who user address space and kernel address are disjoint. x86 and arm has this config option set while s390 does not. If ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE is not set, the bpf old helper `bpf_probe_read()` will not be available. Some existing users may have implicit memory accesses to access user memory, so using `bpf_probe_read_kernel()` will cause their application to fail. Therefore, for non-s390, the rewriter will use `bpf_probe_read()` for these implicit memory accesses. For s390, `bpf_probe_read_kernel()` is used as default and users should use `bpf_probe_read_user()` explicitly when accessing user memories.
+One of jobs for rewriter is to turn implicit memory accesses to explicit ones using kernel helpers. Recent kernel introduced a config option ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE which will be set for architectures whose user address space and kernel address are disjoint. x86 and arm has this config option set while s390 does not. If ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE is not set, the bpf old helper `bpf_probe_read()` will not be available. Some existing users may have implicit memory accesses to access user memory, so using `bpf_probe_read_kernel()` will cause their application to fail. Therefore, for non-s390, the rewriter will use `bpf_probe_read()` for these implicit memory accesses. For s390, `bpf_probe_read_kernel()` is used as default and users should use `bpf_probe_read_user()` explicitly when accessing user memories.
 
 # bcc Python