eclipse: recommend changing the default project make target (#12447)

This is required for example for quickly iterating with a debugger, where
Eclipse will build the project automatically.

It’s also shorter than the previous steps, which I think might not have been
updated since
https://qmk.fm/changes/2017-09-08-making-from-root-and-no-more-makefiles

docs/other_eclipse.md

@@ -50,7 +50,7 @@ This is the most important plugin as it will allow Eclipse to _understand_ AVR C
 ### [ANSI Escape in Console](https://marketplace.eclipse.org/content/ansi-escape-console)
 This plugin is necessary to properly display the colored build output generated by the QMK makefile.
 
-1. Open <kbd><kbd>Help</kbd> > <kbd>Eclipse Marketplace…</kbd></kbd>
+1. Open <kbd>Help</kbd> > <kbd>Eclipse Marketplace…</kbd>
 2. Search for _ANSI Escape in Console_
 3. Click the <samp>Install</samp> button of the plugin
 4. Follow the instructions and agree again with the security warning for unsigned content.
@@ -59,7 +59,7 @@ Once both plugins are installed, restart Eclipse as prompted.
 
 # Configure Eclipse for QMK
 ## Importing the Project
-1. Click <kbd><kbd>File</kbd> > <kbd>New</kbd> > <kbd>Makefile Project with Existing Code</kbd></kbd>
+1. Click <kbd>File</kbd> > <kbd>New</kbd> > <kbd>Makefile Project with Existing Code</kbd>
 2. On the next screen:
   * Select the directory where you cloned the repository as _Existing Code Location_;
   * (Optional) Give a different name to the project¹, e.g. _QMK_ or _Quantum_;
@@ -73,16 +73,18 @@ Once both plugins are installed, restart Eclipse as prompted.
 ¹ There might be issues for importing the project with a custom name. If it does not work properly, try leaving the default project name (i.e. the name of the directory, probably `qmk_firmware`).
 
 ## Build Your Keyboard
-We will now configure a make target that cleans the project and builds the keymap of your choice.
-
-1. On the right side of the screen, select the <kbd>Make Target</kbd> tab
-2. Expand the folder structure to the keyboard of your choice, e.g. `qmk_firmware/keyboards/ergodox`
-3. Right-click on the keyboard folder and select <kbd>New…</kbd> (or select the folder and click the <kbd>New Make Target</kbd> icon above the tree)
-4. Choose a name for your build target, e.g. _clean \<your keymap\>_
-5. Make Target: this is the arguments that you give to `make` when building from the command line. If your target name does not match these arguments, uncheck <kbd>Same as target name</kbd> and input the correct arguments, e.g. `clean <your keymap>`
-6. Leave the other options checked and click <kbd>OK</kbd>. Your make target will now appear under the selected keyboard.
-7. (Optional) Toggle the <kbd>Hide Empty Folders</kbd> icon button above the targets tree to only show your build target.
-8. Double-click the build target you created to trigger a build.
-9. Select the <kbd>Console</kbd> view at the bottom to view the running build.
+
+We will now change the default make target of the the project from `all` to the
+specific keyboard and keymap combination we are working on,
+e.g. `kinesis/kint36:stapelberg`. This way, project-wide actions like cleaning
+and building the project will complete quickly, instead of taking a long time or
+outright locking up Eclipse.
+
+1. Focus an editor tab within the project
+2. Open the `Project` > `Properties` window, then select the `C/C++ Build` list
+   entry and switch to the `Behavior` tab.
+3. Change the default `Make build target` text fields for all enabled builds
+   from `all` to e.g. `kinesis/kint41:stapelberg`.
+4. Verify your setup works by selecting `Project` > `Clean...`.
 
   [1]: https://en.wikipedia.org/wiki/Eclipse_(software)