doc: Clean up undefined anchor links

Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
Reviewed-by: Elena Zannoni <elena.zannoni@oracle.com>

Author: euloh

doc/userguide/index.md

@@ -7,7 +7,7 @@
         -   [Install DTrace on Oracle Linux 9](how-to/dtrace-howto-install-dtrace.md#install_dtrace_oracle_linux_9)
         -   [Install DTrace on Oracle Linux 8](how-to/dtrace-howto-install-dtrace.md#install_dtrace_oracle_linux_8)
         -   [Install DTrace on Oracle Linux 7](how-to/dtrace-howto-install-dtrace.md#install_dtrace_oracle_linux_7)
-        -   [Verify the DTrace Installation](how-to/dtrace-howto-install-_dtrace.md#verify_install)
+        -   [Verify the DTrace Installation](how-to/dtrace-howto-install-dtrace.md#verify_install)
     -   [List and Enable Probes](how-to/dtrace-howto-list-and-enable-probes.md#list_enable_probes)
     -   [Create a DTrace Script](how-to/dtrace-howto-create-a-dtrace-script.md#dt_create_script)
     -   [Use Predicates For Control Flow](how-to/dtrace-howto-use-predicates.md#dt_preds_dlang)

doc/userguide/reference/dtrace_builtin_variable_reference.md

@@ -31,7 +31,7 @@ Macro arguments
 
 </td><td>
 
-See [Macro Arguments](dtrace_builtin_variable_reference.md#macro_arguments)
+See [Macro Arguments](dtrace_builtin_variable_reference.md#dt_macroa_scrpt)
 
 </td></tr><tr><td>
 
@@ -127,7 +127,7 @@ Target process ID
 
 </td><td>
 
-See [Target Process ID](dtrace_builtin_variable_reference.md#target_process)
+See [Target Process ID](dtrace_builtin_variable_reference.md#targ_proc_id)
 </td></tr><tr><td>
 
 `$uid`
@@ -231,7 +231,7 @@ regardless of whether they're referenced by using the `$arg` or `$$arg` form of
 If the `defaultargs` option is set,
 unspecified arguments that are referenced with the `$$arg` form have the value of the empty string \(`""`\).
 
-### Target Process ID
+### Target Process ID <a id="targ_proc_id">
 
 Use the `$target` macro variable to create scripts to be applied to the user process of interest that you specify with the `-p` option or that you create by using the `dtrace` command with the `-c` option. The D programs that you specify on the command line or by using the `-s` option are compiled after processes are created or grabbed, and the `$target` variable expands to the integer process ID of the first such process.