pgsql: Doc: clarify wording about tool requirements in sourcerepo.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_5_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/6c1860dfec6dba416bf06bfa525a4bb1847ee011

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