Fixes for "Glyph not available" warnings from FOP

With the PostgreSQL 11 release notes acknowledgments list, FOP reported

WARNING: Glyph "?" (0x144, nacute) not available in font "Times-Roman".
WARNING: Glyph "?" (0x15e, Scedilla) not available in font "Times-Roman".
WARNING: Glyph "?" (0x15f, scedilla) not available in font "Times-Roman".
WARNING: Glyph "?" (0x131, dotlessi) not available in font "Times-Roman".

This is because we have some new contributors whose names use letters
that we haven't used before, and apparently FOP can't handle them out
of the box.

For now, just fix this by "unaccenting" those names.  In the future,
maybe this can be fixed better with a different font configuration.

There is also another warning

WARNING: Glyph "?" (0x3c0, pi) not available in font "Times-Roman".

but that existed in previous releases and is not touched here.

doc/src/sgml/release-11.sgml

@@ -3144,7 +3144,7 @@ same commits as above
 
    <simplelist>
     <member>Abhijit Menon-Sen</member>
-    <member>Adam Bielański</member>
+    <member>Adam Bielanski</member>
     <member>Adam Brightwell</member>
     <member>Adam Brusselback</member>
     <member>Aditya Toshniwal</member>
@@ -3402,7 +3402,7 @@ same commits as above
     <member>Rod Taylor</member>
     <member>Rushabh Lathia</member>
     <member>Ryan Murphy</member>
-    <member>Şahap Aşçı</member>
+    <member>Sahap Asci</member>
     <member>Samuel Horwitz</member>
     <member>Scott Ure</member>
     <member>Sean Johnston</member>