Fix sidebar links in intrinsics pages (#606)

These extra hashes are causing pages to render incorrectly; notably the
"On this page" sidebar is not populated on the following pages:

- https://fortran-lang.org/learn/intrinsics/array/
- https://fortran-lang.org/learn/intrinsics/character/
- https://fortran-lang.org/learn/intrinsics/system/

Author: jamesgk

source/learn/intrinsics/_pages/GET_COMMAND.md

@@ -107,5 +107,3 @@ Fortran 2003
 [**command_argument_count**(3)](#command_argument_count)
 
 _fortran-lang intrinsic descriptions (license: MIT) \@urbanjost_
-
-#

source/learn/intrinsics/_pages/GET_COMMAND_ARGUMENT.md

@@ -147,5 +147,3 @@ Fortran 2003
 [**command_argument_count**(3)](#command_argument_count)
 
 _fortran-lang intrinsic descriptions (license: MIT) \@urbanjost_
-
-#

source/learn/intrinsics/_pages/GET_ENVIRONMENT_VARIABLE.md

@@ -148,5 +148,3 @@ Fortran 2003
 [**get_command**(3)](#get_command)
 
 _fortran-lang intrinsic descriptions (license: MIT) \@urbanjost_
-
-#

source/learn/intrinsics/_pages/RANK.md

@@ -165,5 +165,3 @@ Results:
 - [**btest**(3)](#btest) - Tests a bit of an _integer_ value.
 
 _fortran-lang intrinsic descriptions (license: MIT) \@urbanjost_
-
-#

source/learn/intrinsics/_pages/REPEAT.md

@@ -87,5 +87,3 @@ Functions that perform operations on character strings:
   [**trim**(3)](#trim)
 
 _fortran-lang intrinsic descriptions (license: MIT) \@urbanjost_
-
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