[COMMITTERS] pgsql: Doc: clarify wording about tool requirements insourcerepo.sgml.

Doc: clarify wording about tool requirements in sourcerepo.sgml.

Original wording had confusingly vague antecedent for "they", so replace
that with a more repetitive but clearer formulation.  In passing, make the
link to the installation requirements section more specific.  Per gripe
from Martin Mai, though this is not the fix he initially proposed.

Discussion: https://postgr.es/m/CAN_NWRu-cWuNaiXUjV3m4H-riWURuPW=j21bSaLADs6rjjzXgQ@mail.gmail.com

Branch
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REL9_3_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/1b2e875e5fae174913dc3955556ab4ee845fc9a6

Modified Files
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doc/src/sgml/sourcerepo.sgml | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)