Remove syntax highlighting in docs

doc/unordered/debuggability.adoc

@@ -33,29 +33,29 @@ All containers and iterators have a custom GDB pretty-printer.
 
 Always, when using pretty-printers, you must enable pretty-printing like below. This is typically a one-time setup.
 
-```
+```plaintext
 (gdb) set print pretty on
 ```
 
 By default, if you compile into an ELF binary format, your binary will contain the Boost.Unordered pretty-printers. To use the embedded pretty-printers, ensure you allow auto-loading like below. This must be done every time you load GDB, or add it to a ".gdbinit" file.
 
-```
+```plaintext
 (gdb) add-auto-load-safe-path [/path/to/executable]
 ```
 
 You can choose to compile your binary _without_ embedding the pretty-printers by defining `BOOST_ALL_NO_EMBEDDED_GDB_PRINTERS`, which disables the embedded GDB pretty-printers for all Boost libraries that have this feature.
 
 You can load the pretty-printers externally from the non-embedded Python script. Add the script, link:https://github.com/boostorg/unordered/blob/develop/extra/boost_unordered_printers.py[/extra/boost_unordered_printers.py], using the `source` command as shown below.
 
-```
+```plaintext
 (gdb) source [/path/to/boost]/libs/unordered/extra/boost_unordered_printers.py
 ```
 
 === Visualization structure
 
 The visualizations mirror the standard unordered containers. The map containers display an association from key to mapped value. The set containers display an association from index to value. An iterator is either displayed with its item, or as an end iterator. Here is what may be shown for an example `boost::unordered_map`, an example `boost::unordered_set`, and their respective begin and end iterators. 
 
-```
+```plaintext
 (gdb) print example_unordered_map
 $1 = boost::unordered_map with 3 elements = {["C"] = "c", ["B"] = "b", ["A"] = "a"}
 (gdb) print example_unordered_map_begin
@@ -76,7 +76,7 @@ Both the SIMD and the non-SIMD implementations are viewable through the GDB pret
 
 For open-addressing containers where xref:#hash_quality_container_statistics[container statistics] are enabled, you can obtain these statistics by calling `get_stats()` on the container, from within GDB. This is overridden in GDB as an link:https://sourceware.org/gdb/current/onlinedocs/gdb.html/Xmethod-API.html[xmethod], so it will not invoke any C++ synchronization code. See the following printout as an example for the expected format.
 
-```
+```plaintext
 (gdb) print example_flat_map.get_stats()
 $1 = [stats] = {[insertion] = {[count] = 5, [probe_length] = {avg = 1.0, var = 0.0, dev = 0.0}}, 
   [successful_lookup] = {[count] = 0, [probe_length] = {avg = 0.0, var = 0.0, dev = 0.0},