docs: fixup broken envvar-role syntax

This needs a leading colon, otherwise it renders as "envvar:" followed
with environment variable using the c-expression role.

Fixes: 4c19426fd6a ("docs/envvars: add missing mesa disk cache envvars")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21896>

diff --git a/docs/envvars.rst b/docs/envvars.rst
index 3f2862d..835ca1e 100644 (file)
--- a/docs/envvars.rst
+++ b/docs/envvars.rst
@@ -230,7 +230,7 @@ Core Mesa environment variables
 
 .. envvar:: MESA_DISK_CACHE_READ_ONLY_FOZ_DBS
 
-   if set with envvar:`MESA_DISK_CACHE_SINGLE_FILE` enabled, references
+   if set with :envvar:`MESA_DISK_CACHE_SINGLE_FILE` enabled, references
    a string of comma separated file paths to read only Fossilize DB
    shader caches for loading at initialization. The file paths are
    relative to the cache directory and do not include suffixes,