Remove/comment out several NYI notes

Part of #4485

Author: coke

doc/Language/5to6-nutshell.rakudoc

@@ -1241,8 +1241,7 @@ Strict mode is now on by default.
 
 Warnings are now on by default.
 
-C<no warnings> is currently L<NYI|/language/glossary#NYI>,
-but putting things in a C<quietly> {} block will silence.
+C<no warnings> can be achieved by wrapping code in a C<quietly> {} block.
 
 =head3 C<autodie>
 

doc/Language/pragmas.rakudoc

@@ -15,9 +15,7 @@ no worries; # don't issue compile time warnings
 =end code
 
 Following is a list of pragmas with a short description of each
-pragma's purpose or a link to more details about its use.  (Note:
-Pragmas marked "[NYI]" are not yet implemented, and those marked "[TBD]"
-are to be defined later.)
+pragma's purpose or a link to more details about its use.
 
 =head2 X<v6.x|Pragmas,v6.x>
 
@@ -155,14 +153,6 @@ fatal>:
         CATCH { default { say "Caught {.^name}" } }
     } # OUTPUT: «Failure␤»
 
-=head2 X<internals|Pragmas,internals>
-
-[NYI]
-
-=head2 X<invocant|Pragmas,invocant>
-
-[NYI]
-
 =head2 X<isms|Pragmas,isms>
 
 C<[2018.09 and later]>
@@ -235,10 +225,6 @@ which are used to make the core functionality as fast as possible.
 Future optimizations in the code generation of Rakudo may obsolete these
 usages.
 
-=head2 X<parameters|Pragmas,parameters>
-
-[NYI]
-
 =head2 X<precompilation|Pragmas,precompilation>
 
 The default allows precompilation of source code, specifically if used in a

doc/Language/variables.rakudoc

@@ -1100,9 +1100,7 @@ $x = Nil;
 # OUTPUT: «Type check failed in assignment to $x; expected type Int:D cannot be itself…»
 =end code
 
-As the name suggests, this pragma applies only to variables. To effect
-the same behavior on parameters, use the C<use parameters :D> pragma
-(currently NYI in Rakudo).
+As the name suggests, this pragma applies B<only> to variables.
 
 =head1 Special variables
 

doc/Type/IO/CatHandle.rakudoc

@@ -695,22 +695,4 @@ IO::CatHandle.new($f1, $f2).words.raku.say;
 Note: if C<:$close> is C<False>, fully-consumed handles are B<still> going
 to be closed.
 
-=head1 NYI Methods
-
-The C<IO::CatHandle> type overrides these methods
-to throw a L«C<X::NYI>|/type/X::NYI» exception.
-
-    multi method flush(|)
-    multi method nl-out(|)
-    multi method out-buffer(|)
-    multi method print(|)
-    multi method printf(|)
-    multi method print-nl(|)
-    multi method put(|)
-    multi method say(|)
-    multi method write(|)
-    multi method WRITE(|)
-    multi method READ(|)
-    multi method EOF(|)
-
 =end pod