Clarify the runtime directory location in installation docs

book/src/install.md

@@ -133,8 +133,8 @@ pacman -S mingw-w64-ucrt-x86_64-helix
 ```
 
 ## Building from source
-
-Clone the repository:
+Clone the Helix GitHub repository into a directory of your choice:
+We will refer to this directory as `repository_directory`.
 
 ```sh
 git clone https://github.com/helix-editor/helix
@@ -149,7 +149,7 @@ cargo install --path helix-term --locked
 
 This command will create the `hx` executable and construct the tree-sitter
 grammars in the local `runtime` folder. To build the tree-sitter grammars requires
-a c++ compiler to be installed, for example `gcc-c++`.
+a c++ compiler to be installed, for example `gcc-c++` or `clang`.
 
 > 💡 If you are using the musl-libc instead of glibc the following environment variable must be set during the build
 > to ensure tree-sitter grammars can be loaded correctly:
@@ -168,16 +168,18 @@ a c++ compiler to be installed, for example `gcc-c++`.
 
 #### Linux and macOS
 
-Either set the `HELIX_RUNTIME` environment variable to point to the runtime files and add it to your `~/.bashrc` or equivalent:
+The **runtime** directory is in the root of the `repository_directory`, so either
+set the `HELIX_RUNTIME` environment variable to point to the runtime files and
+add it to your `~/.bashrc` or equivalent:
 
 ```sh
-HELIX_RUNTIME=/home/user-name/src/helix/runtime
+HELIX_RUNTIME=repository_directory/helix/runtime
 ```
 
-Or, create a symlink in `~/.config/helix` that links to the source code directory:
+Or, create a symbolic link:
 
 ```sh
-ln -s $PWD/runtime ~/.config/helix/runtime
+ln -s repository_directory/helix/runtime ~/.config/helix/runtime
 ```
 
 #### Windows