Broken style guide fixes

[dennisafa]

Style guide links in docs/Contributing.md and style/styleguide.md were broken. (referencing #67)
Very quick fix so didn't feel like the full template was relevant here.

[onvm]

In response to PR creation

CI Message

Your results will arrive shortly

[onvm]

In response to PR creation

CI Message

Run successful see results:
[Results from nimbnode30]
Median TX pps for Speed Tester: 35226655

Linter Failed

examples/arp_response/arp_response.c:284: Lines should be <= 120 characters long [whitespace/line_length] [5]
Total errors found: 1
examples/flow_table/openflow.h:50: Using deprecated casting style. Use static_cast(...) instead [readability/casting] [4]
examples/flow_table/openflow.h:569: Extra space before ( in function call [whitespace/parens] [4]
examples/flow_table/openflow.h:634: Extra space before ( in function call [whitespace/parens] [4]
examples/flow_table/openflow.h:771: Extra space before ( in function call [whitespace/parens] [4]
examples/flow_table/openflow.h:804: Extra space before ( in function call [whitespace/parens] [4]
examples/flow_table/openflow.h:865: Extra space before ( in function call [whitespace/parens] [4]
examples/flow_table/openflow.h:926: Extra space before ( in function call [whitespace/parens] [4]
Total errors found: 7
examples/nf_router/nf_router.c:173: Lines should be <= 120 characters long [whitespace/line_length] [5]
Total errors found: 1
examples/payload_scan/payload_scan.c:95: Lines should be <= 120 characters long [whitespace/line_length] [5]
examples/payload_scan/payload_scan.c:114: Almost always, snprintf is better than strcpy [runtime/printf] [4]
examples/payload_scan/payload_scan.c:126: Lines should be <= 120 characters long [whitespace/line_length] [5]
Total errors found: 3
onvm/onvm_mgr/onvm_pkt.c:68: Are you taking an address of a cast? This is dangerous: could be a temp var. Take the address before doing the cast, rather than after [runtime/casting] [4]
Total errors found: 1
onvm/onvm_mgr/onvm_stats.c:306: If an else has a brace on one side, it should have it on both [readability/braces] [5]
Total errors found: 1
onvm/onvm_nflib/onvm_pkt_common.c:98: Are you taking an address of a cast? This is dangerous: could be a temp var. Take the address before doing the cast, rather than after [runtime/casting] [4]
Total errors found: 1

[koolzz]

Also nice