docs: replace most uses of `meson_options.txt` with `meson.options`

I've left the old release notes in place, but updated everything else to
use `meson.options`

docs/markdown/Adding-new-projects-to-wrapdb.md

@@ -106,7 +106,7 @@ Remember that all files go in the directory
 `subprojects/packagefiles/<project-name>`.
 
 ```
-${EDITOR} meson.build meson_options.txt
+${EDITOR} meson.build meson.options
 ```
 
 In order to apply the locally added build files to the upstream

docs/markdown/Build-options.md

@@ -7,8 +7,9 @@ short-description: Build options to configure project properties
 Most non-trivial builds require user-settable options. As an example a
 program may have two different data backends that are selectable at
 build time. Meson provides for this by having a option definition
-file. Its name is `meson_options.txt` and it is placed at the root of
-your source tree.
+file. Its name is `meson.options` and it is placed at the root of
+your source tree. For versions of meson before 1.1, this file was called
+`meson_options.txt`.
 
 Here is a simple option file.
 

docs/markdown/Configuring-a-build-directory.md

@@ -7,7 +7,7 @@ short-description: Configuring a pre-generated build directory
 Often you want to change the settings of your build after it has been
 generated. For example you might want to change from a debug build
 into a release build, set custom compiler flags, change the build
-options provided in your `meson_options.txt` file and so on.
+options provided in your `meson.options` file and so on.
 
 The main tool for this is the `meson configure` command.
 

docs/markdown/Fs-module.md

@@ -16,7 +16,7 @@ If specified, a leading `~` is expanded to the user home directory.
 Environment variables are not available as is the rule throughout Meson.
 That is, $HOME, %USERPROFILE%, $MKLROOT, etc. have no meaning to the Meson
 filesystem module. If needed, pass such variables into Meson via command
-line options in `meson_options.txt`, native-file or cross-file.
+line options in `meson.options`, native-file or cross-file.
 
 Where possible, symlinks and parent directory notation are resolved to an
 absolute path.

docs/markdown/IDE-integration.md

@@ -338,7 +338,7 @@ The output format is as follows:
 ```json
 [
     "/Path/to/the/targets/meson.build",
-    "/Path/to/the/targets/meson_options.txt",
+    "/Path/to/the/targets/meson.options",
     "/Path/to/the/targets/subdir/meson.build"
 ]
 ```

docs/markdown/Porting-from-autotools.md

@@ -150,7 +150,7 @@ else
 endif
 ```
 
-`meson_options.txt`:
+`meson.options`:
 
 ```meson
 option('enable-dep11', type : 'boolean', value : true, description : 'enable DEP-11')