add note about RAM issues

Author: jvdp1

README.md

@@ -58,6 +58,8 @@ cmake --build build
 cmake --build build --target test
 ```
 
+
+
 ### Build with make
 
 Alternatively, you can build using provided Makefiles:
@@ -66,6 +68,25 @@ Alternatively, you can build using provided Makefiles:
 make -f Makefile.manual
 ```
 
+## Memory issues during compilation
+
+Some issues can be encountered during compilation on low RAM computers.
+These issues are due to the high number of procedures generated by the preprocessor.
+They can be avoided by limiting the maximum rank of generated procedures, as follows with `CMake`:
+
+```sh
+cmake -B build
+
+cmake --build build -DCMAKE_MAXIMUM_RANK=4
+
+cmake --build build --target test
+```
+or as follows with `make`:
+
+```sh
+make -f Makefile.manual FYPPFLAGS=-DMAXRANK=4
+```
+
 ## Documentation
 
 Documentation is a work in progress (see issue #4) but is currently available at https://stdlib.fortran-lang.org.