Fix docs using -D instead of -G (#73)

- omnitrace-avail option is -G, not -D

source/docs/runtime.md

@@ -15,7 +15,7 @@ propagated to `omnitrace-avail`, thus it should be viewed as the single source o
 information or missing feature is found in this documentation.
 
 It is recommended to create a default configuration file in `${HOME}/.omnitrace.cfg`. This can be done via
-executing `omnitrace-avail -D ~/.omnitrace.cfg`, or optionally, use `omnitrace-avail -D ~/.omnitrace.cfg --all`
+executing `omnitrace-avail -G ~/.omnitrace.cfg`, or optionally, use `omnitrace-avail -G ~/.omnitrace.cfg --all`
 for a verbose configuration file with descriptions, categories, etc.
 
 Modify `${HOME}/.omnitrace.cfg` as desired, e.g. enable [perfetto](https://perfetto.dev/),
@@ -85,7 +85,7 @@ omnitrace-avail --hw-counters --description
 #### Generating Default Configuration
 
 ```console
-$ omnitrace-avail -D ~/.omnitrace.cfg
+$ omnitrace-avail -G ~/.omnitrace.cfg
 [omnitrace-avail] Outputting text configuration file '/home/user/.omnitrace.cfg'...
 $ cat ~/.omnitrace.cfg
 # auto-generated by omnitrace-avail (version 1.2.0) on 2022-06-27 @ 19:15
@@ -762,7 +762,7 @@ $ omnitrace-avail -H -bd
 ## Creating a Configuration File
 
 [Omnitrace](https://github.com/AMDResearch/omnitrace) supports 3 configuration file formats: JSON, XML, and plain text.
-Use `omnitrace-avail -D <filename> -F txt json xml` to generate default configuration files of each format and, optionally,
+Use `omnitrace-avail -G <filename> -F txt json xml` to generate default configuration files of each format and, optionally,
 include the `--all` flag for descriptions, etc.
 Configuration files are specified via the `OMNITRACE_CONFIG_FILE` environment variable
 and by default will look for `${HOME}/.omnitrace.cfg` and `${HOME}/.omnitrace.json`.