Add troubleshooting for pkgconfig errors on fedora (bevyengine#5821)

# Objective

- There can be a confusing pkgconfig error on fedora.

## Solution

- Add troubleshooting guide for pkgconfig errors on fedora.

---

cc bevyengine#2826
cc bevyengine#5738

Co-authored-by: Carter Anderson <mcanders1@gmail.com>

docs/linux_dependencies.md

@@ -55,6 +55,35 @@ Add your arch to the end of the package to remove the linker error. For example:
 sudo dnf install alsa-lib-devel.x86_64
 ```
 
+Or if there are errors such as:
+
+```txt
+  --- stderr
+  thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: "`\"pkg-config\" \"--libs\" \"--cflags\" \"libudev\"` did not exit successfully: exit status: 1\n--- stderr\nPackage libudev was not found in the pkg-config search path.\nPerhaps you should add the directory containing `libudev.pc'\nto the PKG_CONFIG_PATH environment variable\nNo package 'libudev' found\n"', /home/<user>/.cargo/registry/src/github.com-1ecc6299db9ec823/libudev-sys-0.1.4/build.rs:38:41
+  stack backtrace:
+     0: rust_begin_unwind
+               at /rustc/9bb77da74dac4768489127d21e32db19b59ada5b/library/std/src/panicking.rs:517:5
+     1: core::panicking::panic_fmt
+               at /rustc/9bb77da74dac4768489127d21e32db19b59ada5b/library/core/src/panicking.rs:96:14
+     2: core::result::unwrap_failed
+               at /rustc/9bb77da74dac4768489127d21e32db19b59ada5b/library/core/src/result.rs:1617:5
+     3: core::result::Result<T,E>::unwrap
+               at /rustc/9bb77da74dac4768489127d21e32db19b59ada5b/library/core/src/result.rs:1299:23
+     4: build_script_build::main
+               at ./build.rs:38:5
+     5: core::ops::function::FnOnce::call_once
+               at /rustc/9bb77da74dac4768489127d21e32db19b59ada5b/library/core/src/ops/function.rs:227:5
+  note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
+warning: build failed, waiting for other jobs to finish...
+error: build failed
+```
+
+Set the `PKG_CONFIG_PATH` env var to `/usr/lib/<target>/pkgconfig/`. For example on an x86_64 system:
+
+```txt
+export PKG_CONFIG_PATH="/usr/lib/x86_64-linux-gnu/pkgconfig/"
+```
+
 ## Arch / Manjaro
 
 ```bash