pgsql: Adjust auto_explain's GUC descriptions.

Adjust auto_explain's GUC descriptions.

This commit adjusts auto_explain's GUC descriptions to follow the
style guidelines established by commit 977d865c36.  Specifically,
it ensures the accepted special values are listed in a consistent
manner.

Author: Ilia Evdokimov <ilya.evdokimov@tantorlabs.com>
Reviewed-by: Peter Smith <smithpb2250@gmail.com>
Discussion: https://postgr.es/m/e82d4647-ce7f-45c7-9b01-fb900a050767%40tantorlabs.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e636da92002857c24f8b66b6ac4a47ff91803c06

Modified Files
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contrib/auto_explain/auto_explain.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)