docs(iaas): update description of sna routing table commands

[marceljk]

Description

relates to #1656 (comment)

Checklist

• Issue was linked above
• Code format was applied: make fmt
• Examples were added / adjusted (see e.g. here)
• Docs are up-to-date: make generate-docs (will be checked by CI)
• Unit tests got implemented or updated
• Unit tests are passing: make test (will be checked by CI)
• No linter issues: make lint (will be checked by CI)

[github-actions]

Merging this branch will not change overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable	0.00% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/create	58.14% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/delete	34.29% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/describe	75.93% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/list	69.81% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route	0.00% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/create	64.38% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/delete	36.11% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/describe	75.93% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/list	63.27% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/update	53.06% (ø)
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/update	56.00% (ø)

Coverage details

_{Compared to commit 7582a94 (run #38273203370)}

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/create/create.go	58.14% (ø)	43	25	18
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/delete/delete.go	34.29% (ø)	35	12	23
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/describe/describe.go	75.93% (ø)	54	41	13
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/list/list.go	69.81% (ø)	53	37	16
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/create/create.go	64.38% (ø)	73	47	26
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/delete/delete.go	36.11% (ø)	36	13	23
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/describe/describe.go	75.93% (ø)	54	41	13
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/list/list.go	63.27% (ø)	49	31	18
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/route.go	0.00% (ø)	8	0	8
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/route/update/update.go	53.06% (ø)	49	26	23
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/routingtable.go	0.00% (ø)	4	0	4
github.com/stackitcloud/stackit-cli/internal/cmd/network-area/routingtable/update/update.go	56.00% (ø)	50	28	22

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.