[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_4_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/4d93184ab3221f3b012bbe1b36b721d2b62f2526

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