[PWGLF] Add README for strangeness table converters

PWGLF/TableProducer/Strangeness/Converters/README.md

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+# Strangeness table converters
+
+Converter tasks migrate old versions of the strangeness derived-data tables to
+newer ones, so that analyses written against the current data model can still
+run over older derived data. Each task reads one or more legacy tables and
+produces the corresponding newer version, filling any column that did not exist
+in the old table with a dummy value.
+
+Add the workflow you need to your job with `o2-analysis-lf-<name>`; only the
+converters whose *input* tables are actually present in your derived data need
+to be enabled.
+
+The table below is generated automatically from the sources.
+
+| Converter | Reads | Produces | Description |
+|---|---|---|---|
+| `stracentconverter.cxx` | `StraCents_000` | `StraCents_001` | Converts Stra Cents from 000 to 001 |
+| `stracentconverter2.cxx` | `StraCents_001` | `StraCents_002` | Converts Stra Cents from 001 to 002 |
+| `stradautracksconverter.cxx` | `V0Cores` + `V0Extras` + `V0TOFs`, `CascCores` + `CascExtras` + `CascTOFs`, `DauTrackExtras` *(=DauTrackExtras_003)* | `DauTrackTOFPIDs_000` |  |
+| `stradautracksextraconverter.cxx` | `DauTrackExtras_000` | `DauTrackExtras_001` | Converts V0 version 001 to 002 |
+| `stradautracksextraconverter2.cxx` | `DauTrackExtras_001` | `DauTrackExtras_002` | Converts daughter TracksExtra from 1 to 2 |
+| `stradautracksextraconverter3.cxx` | `DauTrackExtras_002` | `DauTrackExtras_003` | Converts daughter TracksExtra from 2 to 3 |
+| `stradautrackstofpidconverter.cxx` | `V0Cores` + `V0Extras` + `V0TOFs`, `CascCores` + `CascExtras` + `CascTOFs`, `DauTrackExtras` *(=DauTrackExtras_003)* | `DauTrackTOFPIDs` *(=DauTrackTOFPIDs_003)* |  |
+| `stradautrackstofpidconverter2.cxx` | `StraCollisions`, `DauTrackExtras` *(=DauTrackExtras_003)* + `DauTrackTOFPIDs_000`, `V0CollRefs` + `V0Cores` + `V0Extras` | `DauTrackTOFPIDs_001`<br>`StraEvTimes_000` | converts DauTrackTOFPIDs_000 to _001 |
+| `stradautrackstofpidconverter3.cxx` | `DauTrackTOFPIDs_001`, `StraEvTimes_000` | `DauTrackTOFPIDs_002`<br>`StraEvTimes_001` | converts DauTrackTOFPIDs_001 to _002 |
+| `stradautrackstofpidconverter4.cxx` | `DauTrackTOFPIDs_002`, `StraCollisions` + `StraStamps` *(=StraStamps_001)* | `DauTrackTOFPIDs_003` | converts DauTrackTOFPIDs_002 to _003 |
+| `stradautrackstpcpidconverter.cxx` | `DauTrackTPCPIDs_000` | `DauTrackTPCPIDs_001` | converts DauTrackTOFPIDs_000 to _001 |
+| `straevselextrasconverter.cxx` | **processAll**: `StraEvSels_005` + `StraEvSelExtras_000`<br>**processStraEvSelsOnly**: `StraEvSels_005` *(off by default)* | `StraEvSelExtras_001` |  |
+| `straevselextrasconverter2.cxx` | `StraEvSels` *(=StraEvSels_006)* | `StraEvSelExtras` *(=StraEvSelExtras_001)* | Produce dummy StraEvSelExtras for analysis subscribing to StraEvSelExtras but not saved in the strangeness derived data (typically when running over pp strangeness derived data) |
+| `straevselsconverter.cxx` | `StraEvSels_000` + `StraRawCents_004` | `StraEvSels_001` | Converts Stra Event selections from 000 to 001 |
+| `straevselsconverter2.cxx` | `StraEvSels_001` | `StraEvSels_002` | Converts Stra Event selections from 000 to 001 |
+| `straevselsconverter2rawcents.cxx` | `StraEvSels_001` | `StraRawCents_004` | Converts V0 version 001 to 002 |
+| `straevselsconverter2rawcents2.cxx` | `StraEvSels_002` | `StraRawCents_004` | Converts V0 version 001 to 002 |
+| `straevselsconverter2rawcents3.cxx` | `StraEvSels_003` | `StraRawCents_004` | Converts V0 version 001 to 002 |
+| `straevselsconverter3.cxx` | `StraEvSels_002` | `StraEvSels_003` | Converts Stra Event selections from 000 to 001 |
+| `straevselsconverter4.cxx` | `StraEvSels_003` | `StraEvSels_004` | Converts Stra Event selections from 000 to 001 |
+| `straevselsconverter5.cxx` | `StraEvSels_004` + `StraStamps` *(=StraStamps_001)* | `StraEvSels_005` | Converts Stra Event selections from 004 to 005 |
+| `straevselsconverter6.cxx` | `StraEvSels_005` | `StraEvSels_006` | Converts Stra Event selections from 005 to 006 |
+| `stramccollisionconverter.cxx` | `StraMCCollisions_000` | `StraMCCollisions_001` | Converts V0 version 001 to 002 |
+| `stramccollisionconverter2.cxx` | `StraMCCollisions_001` | `StraMCCollisions_002` | Converts V0 version 001 to 002 |
+| `stramccollmultconverter.cxx` | `StraMCCollMults_000` | `StraMCCollMults_001` | Converts V0 version 001 to 002 |
+| `stramccollmultconverter2.cxx` | `StraMCCollMults_001` | `StraMCCollMults_002` | Converts V0 version 001 to 002 |
+| `strarawcentsconverter.cxx` | **process000to001**: `StraRawCents_000` *(off by default)*<br>**process002to003**: `StraRawCents_002` *(off by default)* | `StraRawCents_001`<br>`StraRawCents_003` | Converts V0 version 001 to 002 |
+| `strarawcentsconverter2v4.cxx` | `StraRawCents_003` | `StraRawCents_004` | Converts V0 version 001 to 002 |
+| `strastampsconverter.cxx` | `StraStamps_000` | `StraStamps_001` | Converts Stra Stamps from 000 to 001 |
+| `v0coresconverter.cxx` | `V0MCCores_000` | `V0MCCores_001` | Converts V0 version 001 to 002 |
+| `v0coresconverter2.cxx` | `V0MCCores_001` | `V0MCCores_002` | Converts V0 version 001 to 002 |
+| `v0mlscoresconverter.cxx` | `V0Cores` | `V0GammaMLScores`<br>`V0LambdaMLScores`<br>`V0AntiLambdaMLScores`<br>`V0K0ShortMLScores` | Converts V0 version 001 to 002 |
+| `zdcneutronsconverter.cxx` | `StraEvSels` *(=StraEvSels_006)* | `ZDCNeutrons`<br>`ZDCNMCCollRefs` |  |
+
+Notes:
+
+* Tables joined with `+` are subscribed together in a single argument
+  (`soa::Join<...>`); a comma separates independent arguments.
+* `Name *(=Name_00N)*` means the task subscribes to (or produces) the
+  unversioned alias, which currently resolves to version `N` in the data model.
+* Tasks with more than one `process` function list each one separately;
+  a switch marked *off by default* must be enabled explicitly.