Docs: Clarify pgr_createTopology edge table updates and notice (#880)

[sakirr05]

ref #880
This PR clarifies when and how pgr_createTopology updates data during topology creation.

Changes:
Added a note at the start of the “Build a routing topology” section explaining when the edge table is updated

• The effect of clean=true on source/target columns
• Which indexes may be created automatically
• When the vertices table is created
• Minor wording cleanup to remove duplicated phrasing

Files changed:
-doc/src/pgRouting-concepts.rst

Notes:
Documentation-only change
No SQL signatures or C/C++ code modified

Summary by CodeRabbit

• Documentation
  • Clarified topology-building notes to explain effects on edge/source/target columns, potential index creation, and automatic vertices table creation when absent.
  • Made reverse_cost wording consistent — now described as used throughout the documentation.
  • Propagated these documentation updates across relevant sections and translation entries for improved consistency.

[coderabbitai]

Walkthrough

Added documentation clarifications: a new note in "Build a routing topology" describing topology creation effects (edge/source/target modifications, potential index creation, vertices table creation) and changed phrasing to state reverse_cost is used throughout the documentation.

Changes

Cohort / File(s)	Summary
Concept doc doc/src/pgRouting-concepts.rst	Inserted a note on topology creation effects (behavior when clean=true, edge/source/target updates, possible index creation on id, the_geom, source, target, and vertices table creation). Reworded reverse_cost wording to “used throughout”. Changes appear in two locations.
English translations locale/en/LC_MESSAGES/pgrouting_doc_strings.po	Added new msgstr for "Build a routing topology" with the expanded note and updated the reverse_cost string to use “used throughout.”
POT template locale/pot/pgrouting_doc_strings.pot	Updated POT header date and added the new Build a routing topology msgid with empty msgstr; adjusted reverse_cost msgid wording to “used throughout.”

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• Deprecate pgr create topology #2830 — Modifies the same "Build a routing topology" documentation content; likely related.

Suggested labels

Documentation, Topology, Translation

Suggested reviewers

• iosefa
• robe2

Poem

🐰 Hopped into docs with nibbling feet,

Planted notes where topologies meet,
Reverse_cost now sings throughout the page,
Vertices and indices join the stage,
A tiny rabbit cheers the doc’s new beat.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: documenting and clarifying pgr_createTopology's edge table updates and effects during topology creation.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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No actionable comments were generated in the recent review. 🎉

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[coderabbitai]

Actionable comments posted: 2

🤖 Fix all issues with AI agents

In `@doc/src/pgRouting-concepts.rst`:
- Line 506: The sentence still reads "in this documentation ``reverse_cost`` is
used throughout." — if the PR intended to simplify, update that sentence to just
"``reverse_cost`` is used throughout." by replacing the existing phrase
containing "in this documentation ``reverse_cost`` is used throughout." with the
shorter form; otherwise, leave it as-is to keep the current wording. Ensure the
edit targets the sentence that contains the token ``reverse_cost`` so the change
is unambiguous.
- Around line 492-498: The note currently conflates pgr_createTopology and the
manual topology steps; update the note to clearly separate behaviors: state that
pgr_createTopology (now removed) accepted clean=true which conditionally wiped
and reassigned the source and target columns and could create indexes on id,
the_geom, source, target and a vertices table, whereas the manual approach using
pgr_extractVertices plus explicit UPDATE statements always overwrites source and
target unconditionally and does not automatically create indexes or a vertices
table; mention both approaches by name (pgr_createTopology, pgr_extractVertices,
UPDATE) so readers can distinguish the conditional behavior and index creation
specific to pgr_createTopology from the manual workflow.