docs(compilation): update for ENABLE_IP2COUNTRY default flip to YES (#179)

Tracks amule-org/amule#119 (merged 2026-06-12): ENABLE_IP2COUNTRY now
defaults to YES with a configure-time hard-fail if libmaxminddb is
missing, matching how ENABLE_NLS and ENABLE_UPNP have always worked.

docs/developer/compilation/index.md:
  - Build-options table: ENABLE_IP2COUNTRY default flipped NO → YES.
  - BUILD_EVERYTHING note: ENABLE_IP2COUNTRY is no longer the odd-one-out
    that needed an explicit -DENABLE_IP2COUNTRY=YES; rewrite to list it
    alongside ENABLE_NLS and ENABLE_UPNP as a default-on toggle.

docs/developer/compilation/linux.md:
  - "libmaxminddb not found" troubleshooting paragraph: users hitting
    the FATAL_ERROR now usually didn't explicitly opt in; rewrite to
    name the default-YES behaviour as the trigger and point at the
    install-or-opt-out fix.

The per-OS Quick Start cmake invocations (linux/macos/windows/bsd) keep
their explicit -DENABLE_IP2COUNTRY=YES — the doc style elsewhere is
"list every ENABLE_* explicitly even when it matches the default", same
as the existing -DENABLE_NLS=YES / -DENABLE_UPNP=YES entries. Value still
matches the new default.

Author: got3nks

docs/developer/compilation/index.md

@@ -76,7 +76,7 @@ All options are passed as `-DOPTION=YES` or `-DOPTION=NO` to the initial `cmake
 | `ENABLE_NLS` | YES | [Native-language support](../translations/index.md) (gettext) |
 | `TRANSLATED_MANPAGES` | YES | [Translated man pages](#translated-man-pages) rendered via po4a (requires `ENABLE_NLS`; skipped with a notice if po4a is not found) |
 | `ENABLE_UPNP` | YES | [UPnP port forwarding](../../manual/configuration/upnp.md) |
-| `ENABLE_IP2COUNTRY` | NO | IP→country mapping (libmaxminddb) |
+| `ENABLE_IP2COUNTRY` | YES | IP→country mapping (libmaxminddb) |
 | `ENABLE_MMAP` | NO | Use memory-mapped file I/O where supported |
 | `DOWNLOAD_AND_BUILD_DEPS` | NO | When an optional dependency is missing, let CMake download and build it from source instead of failing (requires Git) |
 
@@ -112,7 +112,7 @@ Or, using the `BUILD_EVERYTHING` shorthand:
 cmake -B build -DBUILD_EVERYTHING=YES
 ```
 
-`BUILD_EVERYTHING` turns on every build target (`BUILD_*`), but it does **not** enable `ENABLE_IP2COUNTRY` (which is `NO` by default). Pass `-DENABLE_IP2COUNTRY=YES` alongside it if you want IP→country mapping. `ENABLE_NLS` and `ENABLE_UPNP` are already `YES` by default.
+`BUILD_EVERYTHING` turns on every build target (`BUILD_*`). It does not touch the `ENABLE_*` toggles, but `ENABLE_NLS`, `ENABLE_UPNP`, and `ENABLE_IP2COUNTRY` are all `YES` by default, so a default `BUILD_EVERYTHING` invocation produces a full-feature build provided their respective libraries (`gettext`, `libupnp`, `libmaxminddb`) are installed.
 
 ### Debug Build
 

docs/developer/compilation/linux.md

@@ -255,4 +255,4 @@ You enabled `-DENABLE_UPNP=YES` (the default) but the libupnp headers and librar
 CMake Error: ENABLE_IP2COUNTRY=YES but maxminddb.h was not found.
 ```
 
-You enabled `-DENABLE_IP2COUNTRY=YES` but the libmaxminddb headers (or shared library) are missing. Either install libmaxminddb (`libmaxminddb-dev` on Debian/Ubuntu, `libmaxminddb-devel` on Fedora) or pass `-DENABLE_IP2COUNTRY=NO`.
+`ENABLE_IP2COUNTRY` defaults to `YES`, so any configure without an explicit `-DENABLE_IP2COUNTRY=NO` will hit this when libmaxminddb isn't installed. Either install libmaxminddb (`libmaxminddb-dev` on Debian/Ubuntu, `libmaxminddb-devel` on Fedora) or pass `-DENABLE_IP2COUNTRY=NO` to opt out of the country-flag feature.